Malachi 3:
The Immutability of transcendent God is a divine attribute that God is unchanging in his character. However, the way that he deals with people does change, Joel 2:
God does not change, i.e., God is immutable. This is an attribute of God Himself. God is perfect. His character does not go through a developmental process.
On the other hand, God's dealing with people changes. That's why there is a difference between the OT and the NT. History changes and develops.
These two are different concepts.
See also
Does God change his mind?.
In your OP in the link, you mention the anthropomorphism in the biblical terminology, "he changed his mind", (and I agree with you there). But like with Moses prayer, God responds to our prayers, and like his turning away from destroying Ninevah, he responds to our repentance.
This is sometimes referred to by those who dispute the Immutability, or, particularly, the Simplicity of God, and OFTEN used by those "libertarian free-willers" who dispute predestination and determinism. But to me, that's just "kicking the can further down the road". If God is the maker of all things that are made (John 1), and by logical causation, the first cause of all that is, —(and, for the reader, I did not say immediate cause)—, then he caused those prayers and and the whole scenario, to include even the fact of their sin.
The question, WHY? does God do things this way, comes up, and it is a good question, though usually asked wrong —not just asked to prove that God doesn't do things this way, but that if he does, then why would he not just bypass all this mess instead, since this is all handled by him anyway. I would like to see a good thread on the thought, that we are, even more than the angels, of some kind of ability IN HIM to appreciate and learn of him. To my mind, this is huge...
