The immutability of God is the doctrine that God does not change. He is the same yesterday, today, and forever. He does not grow wiser, stronger, or holier, because He is already infinite in wisdom, strength, and holiness. He does not forget what He once knew, because His knowledge is complete. He does not abandon promises He once made, because His word is as unchanging as His being. "I am the LORD, I do not change" (Malachi 3:6). "Every good gift and every perfect gift is from above, and comes down from the Father of lights, with whom there is no variation or shadow of turning" (James 1:17). "Jesus Christ is the same yesterday, today, and forever" (Hebrews 13:8). Immutability does not mean God is static or inactive — He is infinitely alive. It means that His character is a fixed reference point in a changing universe. When Scripture speaks of God "repenting" (e.g., Genesis 6:6, Jonah 3:10), it uses human language to describe God's consistent response to changing human circumstances — not a change in God but a change in what God relates to. Immutability is enormously practical: if God did not change, then the promises He made yesterday are still good today, and the promises He makes today will still be good when you need them tomorrow. You can stake your life on an unchanging God.