What does it mean that God is immutable?
God's immutability means He never changes. He has not changed in the past, He does not change today, and He will never change in the eternity future. Hebrews declares Jesus Christ is the same yesterday, today, and forever. This is God's unchanging nature.
Les teaches that God has certain attributes we should constantly remind ourselves of. After sovereignty, He points to immutability, using Hebrews: Jesus Christ is the same yesterday, today, and forever. Les explains that God has never changed in the past, has not changed as of today, and will never change in the eternity future. Immutability therefore means God remains unchanged.
Hebrews 13:8
Jesus Christ the same yesterday, and to day, and for ever.