In First Samuel it says that God sent an evil spirit to Saul to torment him. I know what it’s like to go through depression and anxiety, and I don’t understand why God would do that to him. (Other places in the Bible mention similar occurrences of God sending evil: Isaiah 45:7, Judges 9:23, and Jeremiah 6:19, among others.)
Interpreters differ about what this expression means precisely. Some say that the so-called “evil spirit from the LORD” is an actual spirit-being that God allowed to trouble Saul as a punishment for his disobedience. God is not the author of evil and does not tolerate evil in his presence, so if this is the correct interpretation, we shouldn’t think of God having evil spirits waiting around to do his bidding. Rather, the spirit would be “from God” in the sense that its freedom to trouble Saul was a judgment from God.
But this is not the only way to understand the expression. The Hebrew word that describes a spirit-being, ruach, can also be applied to the human spirit. We see the supernatural meaning in Eliphaz’s opening speech in the book of Job, “A spirit glided past my face, and the hair on my body stood on end.” We see the natural, human meaning in Psalm 51, “Create in me a pure heart . . . and renew a steadfast spirit within me.”
In addition, the Hebrew word often translated as “evil” means more generally “bad” or “harmful.” It’s the word used, for example, when Job says, “Shall we receive good from God, and not trouble?” (NIV). Some versions translate this as “evil,” but I don’t think that’s correct, since God is not the source of evil. In the other passages you mentioned, the NIV translates this term as “disaster” (Isaiah and Jeremiah) and “animosity” (Judges), which I think fairly captures the sense—not “evil.”
So the actual meaning of the phrase about Saul could be “a bad spirit from the LORD,” signifying not an actual spirit-being, but rather a dark and foreboding disposition of the human spirit, reflecting the break in Saul’s relationship with God.
A couple of times earlier in Samuel-Kings, we read that “the Spirit of God came powerfully on Saul”—once when Samuel anointed him king, and once when he was inspired to deliver the Israelites from an enemy. Now, unfortunately, we hear that “the Spirit of the LORD had departed from Saul.” Once the Spirit’s presence had been experienced, its absence would be keenly felt. This may be sufficient to explain Saul’s dark moods.
On balance, in my opinion, the first meaning—a spirit-being—seems more likely, given the parallelism in the narrative: “The Spirit of the LORD had departed from Saul, and an evil spirit from the LORD tormented him.”
But whatever this evil or bad spirit was, and however active a role God had in sending it, we need to recognize that God was also gracious to Saul in arranging for David to come to his court and relieve him through music, through a servant who happened to have seen “a son of Jesse of Bethlehem who knows how to play the lyre.”
God allowed Saul the privilege of hearing one of the most gifted musicians in ancient Israel play his lyre and perhaps sing early versions of what became some of the psalms. When David did this, Saul “would feel better, and the evil spirit would leave.” God mercifully tempered the judgment with relief, allowing Saul back into his presence through the worship music he providentially made possible at his court.
I hope that any who experience depression and anxiety today will find this same relief in seeking and finding God’s presence, whether through music, the beauty of creation, the encouragement of God’s word, or some similar means.