A change of mind is invariably due to the acquisition of new knowledge or of a new judgment about reality, but God is perfect in knowledge (Job 37:16), knowing all things (1 John 3:20). Moreover, His perfect knowledge of the world is not derived from the world. He teaches all humans knowledge (Ps. 94:9–11), but no one teaches or informs God (Isa. 40:12–14). For this reason, the Westminster Confession of Faith states that God’s knowledge is “infinite, infallible, and independent upon the creature.” Such omniscience is not susceptible to augmentation, and so, God’s mind is not susceptible to change.
“The Glory of Israel will not lie or change his mind; for he is not a human being, that he should change his mind” (1 Sam. 15:29; cf. Num. 23:19, NIV). These words of the prophet Samuel provide a straightforward reply to the question “Does God change His mind?” Yet in the same chapter, we are told twice that God regretted having made Saul king (1 Sam. 15:11, 35). Indeed, several passages of Scripture describe God as regretting, relenting, or repenting (which fundamentally indicates a change of mind) (e.g., Gen. 6:6–7; Ex. 32:14; 2 Sam. 24:16; Jer. 18:8; Jonah 3:10).
Classical theists understand such passages to be speaking about God anthropomorphically and do not take such descriptions literally. John Gill, for instance, explains Exodus 32:14 in this way:
Not that any of God’s thoughts or the determinations of his mind are alterable; for the thoughts of his heart are to all generations [Ps. 33:11]; but he changes the outward dispensations of his providence, or his methods of acting with men . . . and this being similar to what they do when they repent of anything, who alter their course, hence repentance is ascribed to God, though, properly speaking, it does not belong to him.
This is similar to the non-literal way we understand passages that speak of God having body parts or performing operations proper to bodies (such as smelling, hearing with ears, seeing with eyes, experiencing intestinal disturbance, moving about locomotively in space, etc.). Several theological truths undergird this interpretation and belief that God does not change His mind.
First, Scripture testifies that God is immutable. While God changes the heavens and the earth, He Himself is not among the things He changes: “You will change them like a robe, and they will pass away, but you are the same” (Ps. 102:26–27). God declares, “I, the LORD, do not change” (Mal. 3:6). He is “the Father of lights, with whom there is no variation or shadow” (James 1:17).