The word of the LORD came to Samuel: “I regret that I have made Saul king, for he has turned back from following me and has not performed my commandments.” And Samuel was angry, and he cried to the LORD all night…And Samuel said to him, “The LORD has torn the kingdom of Israel from you this day and has given it to a neighbor of yours, who is better than you. And also the Glory of Israel will not lie or have regret, for he is not a man, that he should have regret…And Samuel did not see Saul again until the day of his death, but Samuel grieved over Saul. And the LORD regretted that he had made Saul king over Israel.” – 1 Sam 15:10-11, 28-29, 35
At the very beginning and very end of this section we are told that God “regrets” that He has made Saul king (15:11, 35). But, between those two verses we are told that God does not “regret” (15:29). How are we to make sense of that?
In verse 29 Samuel is responding to Saul’s request for his sin to be pardoned, but Samuel makes it clear that God’s word of judgment has fallen—he has rejected Saul as being king, so He will not go back on His word; He isn’t a man, so He doesn’t lie, which means when God says He will do something He won’t change His mind (cf. Num 23:19). Samuel makes it clear that when we are told that God “regrets” Saul becoming king it isn’t the regret of God saying, “Oops, I wish I wouldn’t have done that. If only I had known better…”
So what is it then? The “regret” of God here is an anthropomorphism that demonstrates the emotional pain God experiences in Saul’s disobedience. There are two ways to use “regret.” One, is the kind that cannot be associated with God. This is the regret of mistake (what Samuel explicitly denies in vs. 29). The other is the kind that God experiences (in vs. 11 and 35). This is the regret of emotional angst. It is not predicated on God making a mistake, but is an accommodation of typical human experiences (like regret) to convey the interior life of God to us. When we regret something, it is because we did something we wish we hadn’t, and then experience emotional frustration as a consequence. When God “regrets” something, it is the emotional turmoil of the first instance, but with the “I did something wrong” peeled away.
There are things that God’s will permits, but are by no means things He delights in (eg. Ezekiel 18:23; Lam 3:33). This is similar to what we are told in Genesis 6:6 just before the flood, “And the LORD regretted that he had made man on the earth, and it grieved him to his heart.” Our sin doesn’t leave God unmoved–it pains Him (cf. Eph 4:30).
If you read Samuel carefully, you’ll notice in each verse that we are told of God’s regret, we are then immediately told about the prophet Samuel’s emotional state of mind: “I regret that I have made Saul king…And Samuel was angry, and he cried to the LORD all night… Samuel grieved over Saul. And the LORD regretted that he had made Saul king over Israel,” (15:11, 35, possibly a chiasm? God’s regret, Samuel’s emotion, Samuel’s emotion, God’s regret, ABB’A’).
The prophet is the spokesmen and representative of God and his own emotional turmoil is a portrayal of God’s own sadness and anger over Saul’s rebellion.