Strongs on God’s immutability

By (immutability) we mean that the nature, attributes, and will of God are exempt from all change. Reason teaches us that no change is possible in God, whether of increase or decrease, progress or deterioration, contraction or development. All change must be to better or to worse. But God is absolute perfection, and no change to better is possible. Change to worse would be equally inconsistent with perfection. No cause for such change exists, either outside of God or in God himself.

Psalm 102:27—“thou art the same”; Mal. 3:6—“I, Jehovah, change not”; James 1:17—“with whom can be no variation, neither shadow that is out by turning.” Spenser, Faerie Queen, Cantos of Mutability, 8:2—“Then’ gin I think on that which nature sayde, Of that same time when no more change shall be, But steadfast rest of all things, firmly stayed Upon the pillours of eternity; For all that moveth doth in change delight, But henceforth all shall rest eternally With him that is the God of Sabaoth hight; Oh thou great Sabaoth God, grant me that Sabbath’s sight!” Bowne, Philos. of Theism, 146, defines immutability as “the constancy and continuity of the divine nature which exists through all the divine acts as their law and source.”

Strong, A. H. (1907). Systematic theology (pp. 257–259). Philadelphia: American Baptist Publication Society.