How many covenants are there in the Bible?

Q. How many covenants are there in the Bible? If there are too many to list, what are the main ones?

Hebrews 8:7 talks about the first covenant and the second covenant. Is that the Mosaic Covenant and the New Covenant? If so, wouldn’t be more accurate to call the Abrahamic (or Adamic Covenant) the first covenant? How can the Mosaic Covenant be the first covenant and the New Covenant be the second covenant if there are other covenants before and after the Mosaic Covenant (and in between the Mosaic Covenant and the New Covenant)?

Why do we call the 39 books of the Hebrew Bible the Old Testament? Which covenant is the Old Testament a reference to? Is it the Mosaic Covenant or the Abrahamic Covenant? Is it the Mosaic Covenant because that was the main Covenant in those books?

Thank you for your excellent questions. I will answer them according to the way I understand the biblical covenants.

While various people make covenants with each other over the course of the Bible’s story (for example, Jonathan and David), there are five covenants between God and humans, and those provide the framework for the biblical narrative at its highest level:

First, the covenant between God and every living creature, mediated by Noah, in which God promises unconditionally that a flood will never again destroy all life on earth.

Second, the covenant between God and Abraham, unmediated, in which God promises unconditionally to give Abraham descendants, to give those descendants a land in which to live, and to make Abraham a blessing to all nations. God extends this covenant to Isaac and Jacob.

Third, the covenant between God and the Israelites, mediated by Moses, in which God promises, conditional on obedience to his law, to give the Israelites the land of Canaan in which to live and to show their “wisdom and understanding to the nations.”

Fourth, the covenant between God and David, unmediated, in which God promises unconditionally that a descendant of David will always be on the throne of Israel. (Christians believe that while Israel ceased to be a kingdom, this promise is nevertheless being fulfilled in the reign of Jesus the Messiah.)

Fifth, the covenant between God and people of all nations who believe, mediated by Jesus, in which God promises unconditionally to forgive their sins and put his law in their minds and write it on their hearts so that they will know him.

It is clear from the context in the book of Hebrews that when the author refers in 8:7 to “that first covenant,” he is referring to the covenant mediated by Moses and contrasting it with the covenant mediated by Jesus. The word “first” can be well translated as “former.” Many English Bibles say “another” rather than “a second.” So the author of Hebrews only has two covenants in view and is contrasting them. He is not saying that these are the only two covenants or that the covenant mediated by Moses was the first one that God made with humans.

The meaning is the same in the title Old Testament, which means Old Covenant. I like the title in other languages such as French, Ancien Testament, or Spanish, Antiguo Testamento. That suggests the idea of Former Covenant or Covenant of Antiquity. Such titles acknowledge this covenant as one step on the way towards the ultimate covenant between God and humans, the one mediated by Jesus. It is important to recognize, as the book of Hebrews particularly stresses, along with Paul’s writings, that believers are no longer bound to keep the law of that covenant as a law. In that sense it is “old,” meaning no longer in effect. But believers nevertheless keep the law as the Spirit leads them to live according to what God has put in their minds and written in their hearts. So in that sense, it is “of antiquity.”

I hope these responses are helpful.

A reader responded through the “Ask a Question” option:

I found your answer here to be very helpful. I just wanted to ask for clarification on one or two points. You said, ‘The meaning is the same in the title Old Testament, which means Old Covenant.’ So the meaning of Old Testament is the covenant mediated by Moses, correct? Also, does the Hebrew Bible have this name ‘Old Testament’ because the covenant mediated by Moses was the main Covenant in the Hebrew Bible?

In response, I would say yes, the title Old Testament refers to the covenant mediated by Moses, using the word “Old” in the same sense that the book of Hebrews uses the term “first” or “former.” We might also think of this as “old” in the sense of “the covenant that was in effect when Jesus brought the new covenant.” And yes, the covenant mediated by Moses is the main covenant in the Hebrew Bible. It is the focus of most of the writings in the Old Testament.

How do we reconcile the biblical presentation of a young earth with scientific findings?

Q. I cannot reconcile the earth and the entire universe as being only 6,000 years old, and the scientific findings that the “big bang” happened billions of years ago. According to Genesis they were created within the same week. And while on the subject, surely, the all-powerful God did not have to REST on the 7th day. Fact is, He could have created all that He created in 6 days, with a snap of His fingers, if He had wanted to. What gives? Thanks.

Regarding reconciling the biblical presentation of a young earth with scientific findings, let me refer you to another blog of mine, Paradigms on Pilgrimage, which is actually a book in blog form. I wrote it with Dr. Stephen J. Godfrey, curator of paleontology at the Calvert Marine Museum, to address precisely that issue. In the book, we each tell our own story of coming to a satisfying understanding of it.

Regarding God resting, let me refer you to this post, in which I say, in part, commenting on what Exodus says about God, “on the seventh day he rested and was refreshed“:

In what way could an infinitely powerful God be refreshed, if by definition He could never get tired in the first place? Many interpreters consider the “refreshment” of God to be, in effect, the “aaah” feeling He got when He surveyed “all that He had made” and saw that it was “very good.” While God first got this overview at the end of the sixth day, He devoted the entire next day to contemplating and admiring the beauty of the entire finished creation.

If we love everyone, is our love not worth anything?

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.

How are the NT books not written by apostles inspired?

Q. If Luke was not an apostle, how do we explain why we view the Gospel of Luke and the book of Acts as inspired? And who is the author of the book of Hebrews? If the author of the book of Hebrews is unknown, how do we explain why we view the book of Hebrews as inspired?

How do we know the apostle Matthew was the author of the Gospel of Matthew? Also, was the Gospel of Matthew originally written in Greek? Or was the Gospel of Matthew originally written in Hebrew/Aramaic?

The premise behind these questions is that apostolic authorship is the criterion for NT canonicity. In other words, that only books demonstrably written by apostles are inspired and so should be included in the New Testament. But this is actually not the criterion for NT canonicity.

For one thing, as the questions show, it is not possible to apply this principle consistently to all of the NT books that Christians collectively accept as inspired. In addition to Luke, who was not an apostle (although he was a ministry partner and traveling companion of the apostle Paul), the NT authors include James and Jude, who were brothers of Jesus but not apostles. (Paul speaks of these as two different groups in his first letter to the Corinthians, “the other apostles and the Lord’s brothers.”) The NT authors also include Mark, who was not an apostle (although he was Peter’s co-worker and likely composed his gospel from Peter’s memoirs). And then, as noted, there is an anonymous book, Hebrews. If authorship is the criterion but we don’t know who the author of a book is, then such a book certainly does not qualify.

But as I said, authorship is not the criterion. Rather, the principle of canonicity is that the Holy Spirit bore witness to the church corporately, over a period of centuries, about which books were inspired. The books we currently have in the NT, along with some other books, were used widely in worship, teaching, and devotional reading in many different Christian communities throughout the Roman Empire. Over time, a consensus emerged among these communities about which books should be added to the Hebrew Bible to form the Christian canon.

The first complete list we have of the New Testament books as we know them today is in the Easter letter that Athanasius, bishop of Alexandria, wrote to the churches in A.D. 367. He wrote this list very intentionally, to distinguish canonical books from others with similar titles (some purporting to be apostolic, but actually not written by the supposed authors), to make sure that believers would not be “led astray.” Athanasius speaks of these books as “the divinely inspired Scripture, concerning which we have been fully persuaded, as they who from the beginning were eyewitnesses and ministers of the Word, delivered to the Fathers.” (So the criterion is not apostolic authorship, but the books nevertheless have to preserve eyewitness testimony of Jesus.) Athanasius describes these books as “handed down” and “accredited as divine.” He is speaking of the process by which the Christian communities received these books, test-drove them (so to speak), and recognized their inspiration. After listing the books, Athanasius concludes, “These are the fountains of salvation, that he who thirsts may be satisfied with the living words they contain. In these alone the teaching of godliness is proclaimed. Let no one add to these; let nothing be taken away from them.”

So there was a clear, thoughtful, thorough process that led to the recognition of the New Testament canon. But the principle behind that process was not apostolic authorship; it was the principle of the Holy Spirit’s witness to the church corporately.

(Regarding the authorship and composition of the Gospel of Matthew, I have studied it closely in Greek, and personally I can only conclude that it must have been written in Greek. Its use of the forms and terms of that language strikes me as original, the kind of thing we would not find in a translation from another language. The authors of most of the NT books give their own names, but that is not the case with this one, so we do not know for certain who wrote it. The apostle Matthew is considered the author by tradition.)

Balaam and Phinehas

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.

Did Boaz attend Ruth’s first wedding?

Q. Since it says Boaz was a family member of Ruth’s husband, would he have attended their wedding? I thought in Jewish culture the weddings were huge things, would they have met previous to when the Bible story started?

If Mahlon had married Ruth in Bethlehem, I think Boaz would most likely have been present, as a close relative of his mother. But Mahlon met and married Ruth in Moab, and I don’t think that extended family members would have traveled there for the wedding. However, I am not an expert in the ancient culture, and if others know more I hope they will comment.

Why does Peter say that Lot was righteous like Noah?

Q. In his second epistle, Peter refers to Lot as a righteous man, and he ranks him alongside Noah. But it is recorded in Genesis that Lot offered his daughters to the wicked men of Sodom (though fortunately they were spared that fate). What has Peter overlooked, or what was his insight, that inspired him to credit Lot with righteousness at par with Noah?

The similarity that Peter sees between Noah and Lot is that God rescued each of them when he sent general punishment on the places where they were living. Peter writes that God “brought the flood on the ancient world” and “condemned the cities of Sodom and Gomorrah by burning them to ashes,” but he “protected Noah, a preacher of righteousness,” and he “rescued Lot, a righteous man.” Peter’s overall conclusion from this is that “the Lord knows how to rescue the godly from trials and to hold the unrighteous for punishment.” The implication for his readers is that they should stay faithful during the trials they’re experiencing at the hands of the unrighteous, who will receive God’s justice in the end.

But for Peter to make this argument, Lot has to have been “righteous” at least by comparison with those around him—though not necessarily to the same standard as Noah, who was “a righteous man, blameless among the people of his time, who walked faithfully with God.” Peter observes that Lot was “tormented in his righteous soul by the lawless deeds he saw and heard.” So he didn’t approve of the wrong things that the others around him were doing, and he didn’t join in with them. On that basis Peter considers him to have been righteous.

However, when we put Peter’s observations into conversation with other parts of Scripture that talk about Lot, especially the account in Genesis, we get a further lesson, beyond the one about God preserving faithful people through trials. We see what a perilous position it puts us in if we continue to live right in the midst of people who are doing things that are so bad that they torment our souls. Like Lot, we may end up absorbing some of the beliefs and practices of those people without realizing it. I think this is the explanation for why Lot offered his daughters to the mob: Everything he saw and heard around him had “normalized” exposing people to abuse in that way. One take-home is that we need to be very careful about the various media—songs, Internet programming, movies,  television shows, etc.—that we let into our lives. They can normalize things that are contrary to God’s ways and destructive to ourselves and those around us.

So to complement what Peter says here, we should also stress the warning that Paul gives in his second epistle to the Corinthians: “What do righteousness and wickedness have in common? Or what fellowship can light have with darkness?  … Therefore, ‘Come out from them and be separate, says the Lord. Touch no unclean thing, and I will receive you.'”

We need to be in the world to have an influence on the world. But if we start to become of the world, then we need to think more carefully about boundaries and safeguards for our hearts and minds. How close is too close? One good question to ask is, “In what direction is the influence flowing?” While Lot seems to have been trying to safeguard his mind (he reflected on what he saw around him, and he was horrified), he also seems to have been influenced by his surroundings to such an extent that he no longer even protected his family from the worst kinds of abuse.

How were there multiple languages in Genesis 10 when Genesis 11 says the whole earth had one language?

Q. Been doing an in depth study on the Bible. Came across a series of questions from Genesis. Genesis 10:5 says there are multiple clans with multiple languages, but Genesis 11:1 says the whole earth had 1 language. Could you clear this up?

Genesis 11 picks up the biblical narrative where Genesis 9 leaves off. Genesis 10 is an insertion, a genealogy, that describes the descendants of Noah’s sons before the narrative moves on from Noah and his family. So when Genesis 10 describes various languages, this means the languages that those descendants came to speak after the Tower of Babel episode, which follows the genealogy in the book but not in time.

How is receiving “what is due for the things done while in the body” consistent with salvation by faith?

Q. Faith vs. works has always been a troublesome topic for me. I have read all of your posts on this topic. (Thank you so much for the “Categories” listing. It is a wonderful resource.) I have found that James, in particular, has made a lot of sense to me.

But recently I came across 2 Corinthians 5:10, “For we must all appear before the judgement seat of Christ, so that each of us may receive what is due us for the things done while in the body, whether good or bad.” I find that hard to square with salvation based on faith, even when taking into account understandings such as in James’s.

When confused with Scripture, I often find it useful to read the same passage in The Message. It says, “We will appear before Christ and take what’s coming to us as a result of our actions, either good or bad.” That version hasn’t helped me any. 


I find that Paul writes the words you are asking about solidly within the context of salvation by faith. Shortly afterwards, summing up the discussion, Paul says, “Christ’s love compels us, because we are convinced that one died for all” and “God made him who had no sin to be sin for us, so that in him we might become the righteousness of God.” Beforehand, Paul talks about how God as “has given us the Spirit as a deposit, guaranteeing what is to come.” So there is no notion here of conditional salvation, dependent on works.

I would therefore say that when Paul speaks of us receiving “what is due us for the things done while in the body,” he is speaking not of salvation but of rewards. That is a topic about which the Bible does not tell us as much as we might like. But Paul told those same Corinthians, in his first letter, “No one can lay any foundation other than the one already laid, which is Jesus Christ. If anyone builds on this foundation using gold, silver, costly stones, wood, hay or straw, their work will be shown for what it is, because the Day will bring it to light. It will be revealed with fire, and the fire will test the quality of each person’s work. If what has been built survives, the builder will receive a reward. If it is burned up, the builder will suffer loss but yet will be saved—even though only as one escaping through the flames.”

Paul does not tell us what these rewards are, and we don’t find a description of them anywhere else in the Bible. But it is clear that they are not “earned salvation.” Paul says that the only foundation is Jesus Christ, meaning his saving work for us on the cross. Rather, these rewards are some special blessing from God in acknowledgment of faithful service on earth. Certainly they are an incentive to obedience. But we should not obey God in order to get the rewards. We ought to obey God out of joy-filled love and devotion.

I think that if God simply said, “Well done, good and faithful servant,” that would be enough of a reward to satisfy for all eternity.

Why didn’t David repent of polygamy if he was a “man after God’s own heart”?

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.