Category: Christian Living

Q. Jesus repeated that we are to follow His ways and obey God. Jesus’ law and ways were largely found in the OT and the Torah. As Christians today, what is our relationship to be with the law as it is written out in the Torah? Are we to follow it—not to put our hopes of salvation in it, but as a means of obeying Jesus?

The apostle Paul wrote much in his letters about how Christians are to relate to the Law. He said, for one thing, that “the law is good if one uses it properly.” Paul made clear in many of his letters, as you say yourself, that we are not to look to the Law as a means of salvation. That is, we are not to try to become or remain acceptable to God by following the rules in the Law. So how are we to use the Law “properly”?

I would say that the Law has a role for the Christian in both teaching and restraint. Simply stated, the Law teaches us what is and is not in keeping with God’s intentions for human life; knowing that can keep us from doing things that are contrary to the Law. As a pastor, I sometimes had the occasion to ask people who were considering a particular course of action, “Would it make a difference to you to recognize that this would be breaking one of the Ten Commandments?”

The Law, however, is not able to give us the power to do what it commands. As Paul also makes clear in his letters, it is the Holy Spirit who must give us that power. And once the Holy Spirit is living inside us and transforming us (as is the case with everyone who has genuinely trusted in Jesus for salvation), then we can concentrate on positively doing things “against which there is no law,” as Paul writes in Galatians, rather than on negatively avoiding things that are against the Law.

Those things against which there is no law are the “fruit of the Spirit,” the character qualities that God wants to build into our lives: love, joy, peace, patience, kindness, goodness, faithfulness, gentleness, and self-control. Jesus is our example of living out these qualities, and the Holy Spirit inside us encourages us to grow into them. Instead of asking “what rules should govern my conduct here?” we ask “how can I show love here?” or “how can I remain joyful in this situation?”

If we consistently do the things against which there is no law, we will never be breaking the Law; instead, we will be keeping it in its truest sense. The ideal is to reach the place that St. Augustine once described: “Love God, and do what you will.” In other words, nothing that is contrary to God’s wishes will ever proceed from a deep and genuine love for God. The more we grow in our love for God, the more we can act freely and spontaneously as his child, not checking our actions against a set of rules but simply doing what we know will bring him joy.

Q. Please help! I have struggled so hard to believe. I have begged God to take away my doubt and give me the faith and belief in him that He desires. I have done all of this with a truly sincere heart and I have asked all of this in Jesus’ name. Yet no matter how hard I try, no matter how hard I pray and beg God to take away my doubts, I just can’t fully believe.

I hope it will help you to hear that believing fully does not mean having no doubts.

The capacity for faith and the capacity for doubt are the same. If you did not have any doubts about what you believe, you would not be believing it by faith.

Faith is the reasonable belief in something that we cannot prove. Because we cannot prove it, there will always be some doubt about it. But that does not mean that it is not true or that it is not a reasonable thing to believe.

So please stop tormenting yourself for having doubts. They come with the territory of being a Christian. All believers have them. As we grow in our faith, more and more of our doubts are resolved. We come steadily to have more faith and less doubt. But this is a process—a natural process—and we can’t rush it. But that’s okay with God. He knows that we humans are finite and need to grow into our faith.

Here’s how I know that this is okay with God. The gospels record how a man asked Jesus to heal his child: “If you can do anything, help us,” the man said. “‘If you can’?” Jesus responded. “All things are possible for one who believes.” The man replied, “I believe; help my unbelief!” Jesus did not rebuke him and say, “Well, if you really believed, without any unbelief, I would help you, but since you have doubts, you don’t really believe, and so all things are not possible for you.” Instead, recognizing that the man had genuine faith, even though it was still mixed with doubt, Jesus healed the man’s child.

Some ancient manuscripts say that this man “cried out with tears” when he told Jesus that he believed but needed help with his unbelief. Certainly it was very distressing to him to think that he might not believe fully enough for his child to be healed. But Jesus treated him with kindness, mercy, and compassion. And Jesus regards you in the same way that he regarded this man. He does not condemn you. He sympathizes with you and will walk with you on the path to greater and greater faith. Please show yourself the same kindness that Jesus is showing you. Thank you.

Q. I recently came across the concept of non-duality, specifically what Rupert Spira shares about an infinite consciousness as the concept of “I,” that beneath (or above?) our self, thoughts, and feelings, it’s this consciousness that exists. I have been gravitating towards this, but I am concerned that it could be a false teaching that would pull me away from God. Can you help shed some light on this, whether it’s okay for me to believe in this non-duality or the infinite consciousness? I only want to serve one master and that is our Lord.

I must admit that I am not familiar with Rupert Spira or his teachings. Your question is the first that I have heard of them. I’m not sure that I would do justice to them if I tried to track them down and look them over briefly in order to give an opinion in response to your question. So let me respond this way: Do you have peace in your heart about these teachings? Or do they make you, as someone who only wants to serve Jesus, uncomfortable? If they make you uncomfortable, then I would recommend not pursuing them. I am suggesting that you can rely on spiritual discernment—the Holy Spirit in your life leading you into all truth—to decide about the character these teachings. Someone else may have occasion to read and study them thoroughly and give an evaluation of them in the light of biblical truth. But I think for your own purposes at this point, if you have these concerns about them, they are probably better left alone.

Q. Is it permissible for a Christian to drink alcoholic beverages?

As I understand it, this would be a matter of individual conviction. In Romans 14, Paul discusses various things about which Christians of good will can have honest differences of conviction. At the beginning of the discussion, he mentions eating meat (probably in context meaning food offered to idols) and observing the Sabbath. The principles Paul teaches are that each person “should be fully convinced in their own mind” and that everyone should “make every effort to do what leads to peace and to mutual edification.” That means specifically not doing anything that would lead fellow believers to violate their own consciences and fall into sin. At the end of the discussion, Paul says by way of summary, “It is better not to eat meat or drink wine or to do anything else that will cause your brother or sister to fall.” This suggests that he considers whether or not to drink wine also to be a matter of individual conviction, like Sabbath observance and eating meat.

The Bible does stress that drunkenness is a sin. So any Christian who feels the liberty to drink alcoholic beverages such as wine must do so in moderation. This is a second qualification on the freedom, in addition to the mandate not to cause a fellow believer to sin.

I should also note that in that same discussion in Romans, Paul says, “Let us stop passing judgment on one another.” On matters of individual conviction, we answer to God, not to other people’s opinions of what we should or should not do. Paul says this even more strongly in Colossians: “Therefore do not let anyone judge you by what you eat or drink, or with regard to a religious festival, a New Moon celebration or a Sabbath day. These are a shadow of the things that were to come; the reality, however, is found in Christ.” Ideally we can recognize that choices that rest on individual conviction are minor matters, and we can concentrate on major matters, which have to do with how we can all grow up into the image of Christ.

Q. What should a Christian do if he is currently struggling with understanding the doctrine of the Trinity? What should he do if he he is having a hard time viewing God as being one God who is three persons at the same time (i.e. that it seems hard to differentiate the doctrine of the Trinity from the idea of there being three Gods)? Should he just accept the doctrine of the Trinity on faith and accept on faith that the doctrine of the Trinity is monotheistic (e.g. “This is what the Bible teaches, and I know that the Bible is true, even though I don’t really understand the doctrine very well”)?

I think that one thing a Christian can do who is struggling with the doctrine of the Trinity is to recognize that the Christian faith involves many things that are paradoxes. A paradox consists of two things that seem as if they both cannot be true at the same time, but which are actually both true.

One paradox of the Christian faith is that God is three, but also one. But there are also other paradoxes. The kingdom of God is already here, but it is not here yet. Jesus on earth was both fully human and fully divine. God is completely sovereign, and yet human beings are morally accountable. And so forth.

The way to come to terms with a paradox that the Bible teaches is not to choose one side over the other, but to recognize that the truths of God surpass the capabilities of our human minds. We can trust what God has revealed to us in his word even if our minds are not yet able to grasp how two things that his word affirms can both be true at the same time. It may be helpful to think of the analogy of a child not understanding, for example, why his parents, who supposedly love him, are punishing him. The child is not yet able to understand that discipline is an expression of love. The child only feels hurt and humiliated, and people who love you are not supposed to hurt and humiliate you. But hopefully the child will appreciate, relatively young in life, that good parents correct and discipline a child for his own good, and that it is actually much less loving not to discipline a child.

Perhaps another way to come to terms with the doctrine of the Trinity is to work to understand it in light of what I think is the best analogy we have available here on earth. We don’t know any other beings who are both three and one, but we can consider that the spouses in a healthy marriage are two who have become one. There is no loss of individuality; rather, individuality is actually enhanced. But something beyond the individuals has also come into being, and yet it consists of those individuals: a married couple. That couple functions as a being of its own in many ways. For example, while the spouses have each other’s company, “sometimes the couple gets lonely,” as my late wife used to say, and the couple needs the company of another couple or of other couples.

Personally I also find it helpful to appreciate the implications of the doctrine of the Trinity. It means that at the core of God’s being is relationship, community, cooperation, and interdependence. Humans are created in God’s image, and so when we cultivate and experience these things as true worshipers of God, we are sharing in the essence of God. That is something that the doctrine of the Trinity has for us even though we are not able to grasp it fully with our minds. So I hope you will not see that doctrine as a burden, something you have to believe even though it is impossible for your mind to understand. That would be a burden indeed. Rather, see it as a doctrine that reveals something about the nature of God, by which I mean not his threeness and oneness, but his essential relationalness.

Well, my spell-checker is having trouble with the words in that last sentence! That shows how hard it is to put the doctrine of the Trinity into words. But that doesn’t mean that we can’t put it into practice.

Q. I went to church Sunday. When I got home, everything went wrong.
Could Satan be messing with me?

The Bible teaches clearly that all those who seek to follow and obey God in this life will encounter opposition from “the world,” “the flesh,” and “the devil.” These phrases refer, respectively, to the worldwide system of interests opposed to God; to that part of us that wants to live without regard to God; and to evil spiritual beings who hate God and work to defeat those who believe in him. It is often difficult to determine exactly which part of this evil triumvirate we might be up against, and so I find it helpful to think of them as a collective and not try to parse things any more finely. We can just say, “I think I’m up against the world, the flesh, and the devil here.”

However, it is also true that we human beings are perfectly capable of creating problems for ourselves! So when things go wrong, we shouldn’t automatically conclude that we are facing spiritual opposition. Nevertheless, sometimes, through spiritual discernment, we do get a sense that it is happening. Recently I suffered a minor injury right at a time when I needed good health and strength to do some important work for God. I was speaking to my pastor about this, and I said that I suspected the injury could be the result of spiritual opposition, although I also acknowledged that accidents do happen in this world. “We don’t need to blame the devil every time somebody stubs their toe,” I observed. “No,” my pastor replied, “but you can tell.”

I think that often we can indeed tell. The fact that you made a connection between going to church and “everything going wrong” when you got home suggests that perhaps, by spiritual discernment, you did recognize that “Satan was messing with you.” (That is, that you were up against the world, the flesh, and the devil.) I don’t know whether you meant that you had returned to church after some time of not attending, but if that was the case, then it would surely be likely that you would encounter turbulence as you moved from one set of commitments and activities to another set that reflected a renewed resolve to follow God. But even if you were already attending regularly, there might have been something in the experience of attending worship that day that had inspired deeper and stronger devotion, and it would not be a surprise if you encountered turbulence after that as well.

I would say that the most important thing to keep in mind in such situations is that the main goal of the forces opposed to God is to get you to act unlike a child of God. As one of my professors in seminary used to say, for as long as God has purposes to accomplish through you on this earth, “you are immortal.” The forces opposed to God cannot take you out. But if they can make you act unlike the son or daughter of God that you are, then that is a partial victory for them.

So even if one thing after another goes wrong and you are getting very frustrated, ask yourself, “How can I act as a child of God in this situation?” Recently an online vendor cancelled an order that I had placed and paid for, and the vendor only refunded a small part of the purchase price. Several weeks later, I am still trying to sort this out. But it dawned on me, when I first recognized the problem, “This is my chance to be nice.” I have made an effort to be very courteous with every person I have spoken with on the phone about this. They have noticed and thanked me for my patience. Will I eventually get the rest of my money back? I certainly hope so! But in the meantime, I want to act in this situation like a son of God.

So, I encourage you to continue attending church. Don’t let the turbulence keep you from that. Instead, you can say, “If the world, the flesh, and the devil are so upset about this, I should really keep doing it!” And if everything goes wrong again when you get home, see that as your chance to live in the situation as a son or daughter of God. God bless you!

Q. Why were certain foods considered unclean in the Old Testament? What was the reason/purpose for this? Why was circumcision required? What was the reason/purpose for this? I know these were based on God’s commandments, but I’m not sure of the reason/purpose. Was it for health reasons? Or something else? If it was for health reasons, doesn’t that imply we should follow these commandments today too?

Both being circumcised and keeping kosher were “insignia,” that is, signs that the people who did those things belonged to God as members of his covenant community.

Regarding circumcision, God said to Abraham, “This is my covenant with you and your descendants after you, the covenant you are to keep: Every male among you shall be circumcised. You are to undergo circumcision, and it will be the sign of the covenant between me and you. … My covenant in your flesh is to be an everlasting covenant.” The Hebrew idiom for making a covenant was to “cut” a covenant, since this often involved a ceremony in which sacrificed animals were cut up and the parties to the covenant walked between the pieces to indicate, “If I break this covenant, may this happen to me!” Circumcision also involves cutting, and in that way it was a symbol for covenant membership. (But note that the Bible only envisions male circumcision. It does not provide any warrant for so-called female circumcision. Women belonged fully to the covenant even though only men were circumcised.)

Distinguishing between “clean” and “unclean” animals (that is, between those that could be eaten and those that could not be eaten) was also a covenant sign. God said to the people of Israel through Moses, “I am the Lord your God, who has set you apart from the nations. You must therefore make a distinction between clean and unclean animals and between unclean and clean birds. … You are to be holy to me because I, the Lord, am holy, and I have set you apart from the nations to be my own.” (The phrases “set apart” and “make a distinction” translate the same Hebrew verb.)

So these provisions in the law were ultimately ways by which the people of Israel were to identify themselves as God’s people. There are some similar “insignia” for the New Covenant, particularly being baptized and observing the Lord’s Supper, but the most important markers of God’s people now are the “fruit of the Spirit,” the character qualities that the Holy Spirit builds into the lives of believers: love, joy, peace, patience, kindness, goodness, faithfulness, gentleness, and self-control. These are the things we should be most careful to build into our lives as God’s people today. I believe we are free to make our own choices about circumcision and kosher.

Q. I came across the following quotes: “If you love everyone, your love isn’t worth anything,” and, “When you’re taught to love everyone, to love your enemies, then what value does that place on love?” How should we respond?

The logic behind the first quote seems to be this: If you love everyone, that means you can only love any given person in a way in which it would be sustainable for you to love every person. Since humans are finite, it is not sustainable for a person to love everyone heroically; therefore, if you love everyone, you cannot love anyone heroically.

One problem with this logic is that it does not recognize that our love for most people is potential. It is potentially heroic, as in the case of people who sacrifice their own lives to save the lives of strangers in situations of disaster. But ordinarily, we are responsible to make a small group of people the recipients of our actual love: our family and friends. It is sustainable for us to love them deeply and sacrificially—heroically. And this will only make us readier to love even strangers heroically should a situation call for that.

Another problem with this logic is that it conceives of love as finite. Human love is certainly finite. But divine love, even as it flows through human beings, is infinite. We do not have to worry that we are diluting divine love to the point where it “isn’t worth anything” if we spread it around among as many people as we encounter as “neighbor” (to use the term that Jesus used). Thomas à Kempis wrote about divine love flowing through humans: “Love feels no burden, thinks nothing of trouble, pleads no excuse of impossibility, attempts what is beyond its strength. While one who does not love grows weary and gives up, one who loves continues on and brings all things to completion.”

The logic behind second quote seems to be that if we treat our family and friends no better than we treat our enemies, then we are not doing anything special to show our family and friends how much they mean to us. The inference is that we should distinguish through our behavior between our enemies and our family and friends, in order to show our family and friends that we truly love them.

Once again there is a problem with this logic. A person who is merciful, gentle, and generous even to enemies will certainly be merciful, gentle, and generous to family and friends. Those qualities, expressed towards enemies, show what is inside that person, and family and friends will be very grateful to be in a close relationship with such a person. But if those qualities are expressed selectively, only towards friends and family, then they are instead indicators of restraints or constraints on behavior. Such selective expression suggests that the person might actually act in an unloving way towards family and friends if not for the social conventions governing behavior towards them.

Indeed, the principle that one should distinguish through behavior between friends and enemies suggests that as soon as a friend or family member falls out of our good graces, we can and should treat them in a less loving way, correlating with their new relational standing. If we become pleased with them again, then we will treat them well again. That is not love. That is manipulation.

So I would respond to these quotes by saying that as Christians, we have the amazing privilege of being channels of infinite, inexhaustible divine love to everyone we meet. Ordinarily we will make our family and friends the focused recipients of the active expression of our love, but honoring Jesus’ example of how to “love our neighbor as ourselves,” we will unleash our potential sacrificial love to all we encounter. We will cultivate the character qualities of a genuinely loving person so that we can naturally and spontaneously be gracious, generous, and merciful to everyone, no matter what relational standing they have with us. In this way, we can turn enemies into friends, and then not even have to ask whether we should treat them any differently.

Q. Give a brief review of the respective ministries of Balaam and Phinehas (Numbers 22–26). How can we connect the dots from their experience that would have meaning in our day ?

To speak about Balaam first, he is one of those fascinating characters in the Old Testament who are outside the covenant community but who somehow seem to know the true God. However, for us today, Balaam unfortunately provides a negative example of disobedience rather than a positive example of obedience.

Balaam’s story basically illustrates the truth of what Paul wrote to Timothy: “Those who want to get rich fall into temptation and a trap and into many foolish and harmful desires that plunge people into ruin and destruction. For the love of money is a root of all kinds of evil. Some people, eager for money, have wandered from the faith and pierced themselves with many griefs.” In Balaam’s case, many others were pierced with grief as well.

The details are clear in the story of Balaam. The Moabite king Balak feels threatened by the Israelites, who are passing through his territory, so he sends messengers to Balaam to hire him to curse the Israelites. Balaam consults God and refuses. But Balak then sends distinguished officials back to Balaam to tell him, “Do not let anything keep you from coming to me, because I will reward you handsomely,” Balaam, having already been told “no” by God, asks God again if he can go. God works through the situation, allowing Balaam to go but inspiring him to bless the Israelites rather than curse them. Balak, furious, tells Balaam, “Now leave at once and go home! I said I would reward you handsomely, but the Lord has kept you from being rewarded.” And the Bible says, “Then Balaam got up and returned home, and Balak went his own way.”

That seems like the end of the story. But we find out later in the Bible that it is not. The very next thing that the book of Numbers says is, “While Israel was staying in Shittim, the men began to indulge in sexual immorality with Moabite women,  who invited them to the sacrifices to their gods. The people ate the sacrificial meal and bowed down before these gods. So Israel yoked themselves to the Baal of Peor. And the Lord’s anger burned against them.” (The context shows that this last sentence means that God sent a plague to kill the Israelites.) It turns out that this was Balaam’s idea. Wanting the money that Balak had promised him, Balaam advised him to ruin Israel by having the Moabite women entice the Israelite men into immorality and idolatry. Balaam knew that this would make God furious and turn God against the Israelites—whom God had just inspired him to bless!

It is hard to overstate the degree of moral culpability here. Knowing that God wants to bless people but instead leading them into grave disobedience so that God will punish them is something that an avowed enemy of God and God’s people would do. But Balaam’s motivation was not so dramatically diabolical. It was insipidly banal: He wanted money. If we want to connect the dots from his experience and see what meaning it has for us today, we can see it as an illustration of the mandate from another New Testament admonition, at the end of Hebrews: “Keep your lives free from the love of money and be content with what you have, for God has said, ‘Never will I leave you; never will I forsake you.'”

By the way, the ongoing biblical narrative records what happened to Balaam after the end of his story in Numbers. As the book of Joshua records how the various tribes took possession of their shares of the land, it describes how the tribe of Reuben took its share and mentions in passing, “The Israelites also killed Balaam the son of Beor.”

Phinehas is a foil for Balaam in the story, that is, a character who does the opposite thing. In this case, that means he does the right thing. However, the way in which he does it is shocking for contemporary readers, and so we struggle to understand how it really is the right thing.

God tells Moses that the Israelites who led the others into immorality and idolatry with the Moabite women should be executed. This occasioned grief and repentance. But “while Moses and the whole assembly of Israel were weeping at the entrance to the tent of meeting, an Israelite man brought a Midianite woman into the camp right before their eyes. When Phinehas son of Eleazar, the son of Aaron, the priest, saw this, he left the assembly, took a spear in his hand, and followed the Israelite into the tent. He drove the spear into both of them, right through the Israelite man and into the woman’s stomach. Then the plague against the Israelites was stopped.”

We can certainly appreciate the zeal that Phinehas felt for the purity of the Israelites’ devotion to God, but we must also wonder about the violence that he used. The question of violence in the Old Testament is a deep and difficult one for thoughtful readers of the Bible; I discuss aspects of it in several posts on this blog, and I would refer you to those posts for a fuller discussion. For our present purposes, let us say about Phinehas that he illustrates a burning zeal for purity of devotion to God, and in that specific regard he provides a positive example for us today. We would certainly not advise anyone today to kill another person because that person was being unfaithful to God. But we would advise people to recognize that devotion to God takes precedence over kinship and friendship relations, and certainly over money.

Maybe the best take-home message for us today is to contrast the tawdry banality of Balaam’s motivation with the single-minded zeal of Phinehas’s motivation, even as we do the challenging work of cultural translation to bring that message from the ancient inspired text into our own world.

Q. David, a “man after God’s own heart,” had concubines, plus many wives. How? Was it said of him that he was a “man after God’s heart” before he took these women, possibly for sexual pleasure? Was it sin to have these concubines and wives … of course, right? Did David write his psalms before he lived like this? I’m struggling to read the Psalms as I did before I had these questions. In church, David is like a hero. He’s called a “man after God’s own heart.” He’s described as “repentant.” Yet he never repented of his polygamy. I was raised in church all my life. It’s always talked up how great David was, but his polygamy is never discussed. Why not? Why didn’t Nathan the prophet point out that ongoing sinful lifestyle he was living out? Ugh.

Thank you for your question. I can certainly appreciate the difficulty you are having reconciling what you have been told all your life about David—that he was just the kind of man God wants men to be—with the impression that David used multiple women for sexual pleasure in an ongoing way.

Let me assure you, first of all, that this is not what God wants men to be. The consistent teaching of the Bible is that men should treat women with honor and respect, not as sexual objects, but as persons of dignity, as joint heirs of the grace of life. Jesus warned men not even to look at women lustfully; he told them it would be better to pluck their eyes out than to keep doing that. Paul wrote to Timothy, his younger protege, “Treat … older women as mothers and younger women as sisters, with absolute purity.”

So how, then, is David called a “man after God’s own heart”? I think the problem is with the way that phrase is being understood and taught. This is one of those phrases that has been lifted out of the King James Version and given a life of its own with a changed meaning. In contemporary American culture, “a person after my own heart” means “just the kind of person I like best.” But that is not what the phrase means in the Bible. It does not refer to David’s character. It refers to his will.

In the context of the phrase, the “heart” stands for the desires, for what a person wants. There is a similar use in 1 Samuel 14:7, only a short time in the biblical narrative after Samuel applies the phrase to David. Saul’s son Jonathan, the crown prince of Israel, wants to attack the Philistines. His armor bearer says to him, “Do all that is in your heart, I am with you according to your heart.” In other words, “Do everything that you want to do, because I will do what you want to do.”

So when Samuel tells Saul in 1 Samuel 13:14, “The Lord has sought for himself a man according to his heart … because you have not obeyed what the Lord commanded you,” this actually means, “The Lord has sought for himself a man who will do what he wants him to do, because you have not done what the Lord wanted you to do.” Paul brought out this meaning when he alluded to this statement in his sermon in the synagogue at Pisidian Antioch: “God testified concerning him, ‘I have found David son of Jesse, a man after my own heart; he will do everything I want him to do.'”

So, as I said, the phrase applies not to David’s character but to David’s will. God meant that when he gave David commands regarding what he should do as king in specific situations, David would obey them. We see this illustrated, for example, in 2 Samuel 5:17–25, where God gives David one set of instructions about how to defeat the Philistines and then, when the same circumstances arise, David goes back to God for instructions, God tells him to do something different, David obeys, and once again he defeats his enemies.

So this, I hope, will at least address the concern about David. We do not need to look to him as an example of everything that God wants a man to be. We simply need to see him as a mostly consistent example of obeying direct commands that he received from God.

But I imagine that this leaves you with another concern—about God. If David would indeed obey direct commands from God, then why didn’t God command David not to keep practicing polygamy?

Actually, God did. God commanded through Moses that future Israelite kings were not to have many wives. God also commanded the king to have a copy of the law of Moses and “read it all the days of his life so that he may learn to revere the Lord his God and follow carefully all the words of this law and these decrees.” David, in effect, should have known better. And it seems that he did pay a great price for not following this law. He married one of his wives, Maakah, the daughter of Talmai king of Geshur, in order to make an alliance with that king. Maakah’s firstborn son, Absalom, eventually led a bloody revolt to try to take the throne away from his father David. Absalom failed and was killed, but this tore the kingdom apart and left David heartbroken for the rest of his life.

We may add that in addition to forming marriage alliances with other kingdoms, kings married multiple wives in order to have many children and ensure that they would have a successor on the throne. David outlived his three oldest sons, so we see why this was a concern. But it must also be acknowledged that having many wives and concubines was an ungodly expression of royal entitlement. We may well wonder whether David not having to practice sexual restraint by remaining faithful to one wife contributed to a sense that he could have any woman he wanted, helping lead to his grievous sin against Bathsheba and Uriah.

So why, indeed, did God not command David directly to repent of polygamy? This is a legitimate concern, and it should be acknowledged as such in church—in preaching. We don’t have to understand everything in the Bible to our satisfaction; I don’t think we ever will in this life. But we should acknowledge that there are things in the Bible that are troubling even for Christians of good will who are committed to the authority and inspiration of the Scriptures. I would hope that this issue would be acknowledged in that way.

If I had to try to answer the question of why God did not directly command David to repent of polygamy, I would say that it seems that, for reasons we do not understand fully, God accommodated certain cultural practices as his redemptive plan unfolded, knowing that the unfolding of the plan would itself ultimately bring these practices to an end among the community of believers and, from there, throughout the world. I have discussed this more fully in the following post, which I invite you to read: What does allowing polygamy say about the character of God?

I hope all of this has been helpful to you. You have a legitimate concern that should be acknowledged.