Thought from Today’s Old Testament Passage:
1 Sam. 15:29: And also the Strength of Israel will not lie nor repent: for he is not a man, that he should repent.
It can be affirmed from the start that God’s essence and character, his resolute determination to punish sin and to reward virtue are unchanging (see Mal. 3:6). These are absolute and unconditional affirmations which Scripture everywhere teaches. But this does not mean that all his promises and warnings are unconditional. Many turn on either an expressed or an implied condition.
The classic example of this conditional teaching is Jeremiah 18:7-10.…
This principle clearly states the condition underlying most of God’s promises and threats even when it is not made explicit, as in the case of Jonah. Therefore, whenever God does not fulfill a promise or execute a threat that he has made, the explanation is obvious: in all of these cases, the change has not come in God, but in the individual or nation….
To assert that God is unchanging does not mean he cannot experience regret, grief and repentance. If unchangeableness meant transcendent detachment from people and events, God would pay an awful price for immutability. Instead, God enters into a relationship with mortal beings that demonstrates his willingness to respond to each person’s action within the ethical sphere of their obedience to his will.
(Walter C. Kaiser, Jr., Hard Sayings of the Old Testament (Downers Grove, IL: InterVarsity Press, 1988), pp. 113-115)