1 Samuel 15 echoes what was said back at a pivotal part of redemptive history about the Lord’s regretting making man, and in this case his regretting of making Saul king, when it was after all God’s idea to make man and it was God’s decree also to make Saul king. Nothing is outside of God’s decree, so we must not take such statements as indicating a change in God, but a condescending to our understanding and language so as to see that it is not from the heart of God to afflict the children of men (cf. Lamentations 3). John Calvin writes on this in his institutes (using the old translation for regret here—“repentance”) saying,
“What then is meant by the term repentance? The very same that is meant by the other forms of expression, by which God is described to us humanly. Because our weakness cannot reach his height, any description which we receive of him must be lowered to our capacity in order to be intelligible. And the mode of lowering is to represent him not as he really is, but as we conceive of him. Though he is incapable of every feeling of perturbation, he declares that he is angry with the wicked. Wherefore, as when we hear that God is angry, we ought not to imagine that there is any emotion in him, but ought rather to consider the mode of speech accommodated to our sense, God appearing to us like one inflamed and irritated whenever he exercises judgment, so we ought not to imagine anything more under the term repentance than a change of action, men being wont to testify their dissatisfaction by such a change. Hence, because every change whatever among men is intended as a correction of what displeases, and the correction proceeds from repentance, the same term applied to God simply means that his procedure is changed. In the meantime, there is no inversion of his counsel or will, no change of his affection. What from eternity he had foreseen, approved, decreed, he prosecutes with unvarying uniformity, how sudden soever to the eye of man the variation may seem to be.”
Man is one who has regrets or repentances, but not God. There is no change in God. What we understand of emotions in ourselves, changes that come upon us due to feelings toward a thing, circumstance, etc. is not something that occurs in God. God relates to us in a way we can understand his ways, expressing in his word that he regrets certain things not because he has changed, but because he wants us to understand his holy will is not in that direction. It displeases God for history to continue to go that way. There we have the biblical idea of regret applied to God. There is not a change in God’s affections, for such things never change, but only in the direction of history, revealing his holy plan. God loves his people, and does for them in this world all things for the sake of his only Son. We should then look at these shifts expressed as divine regret in the Bible not as change in God but change in history so as to accord with Christ’s glory. This is what Samuel says in the same chapter:
1Samuel 15:29 “And also the Glory of Israel will not lie or have regret, for he is not a man, that he should have regret.””
We are expected then to see this seeming contradiction in Scripture is simply answering the question implied in the reading of the text that we will naturally have, “Is God like us in regretting things?” The answer, “No, God is not like us that he should lie or have regret” etc. The point being that Scripture is written in a way that we may understand God and ourselves, and especially that we are not God, but the Lord is God. Without these texts we would not see the necessary contrast between ourselves and our Lord. We would miss something of the glory or strength of the God above by bringing him down in terms of ourselves. The very love of God shown to us in the coming of Christ in the flesh is demonstrative of the unchanging love God has for his people. He did not perform the work for us, that is Christ, so as to change the mind of God, but God so loved the world that he gave his only Son. The gospel is an expression of God’s unchanging love for sinners, without which we would never know apart from grace.