What does the Bible say about the unchangeability of God?

The unchangeability of God, often referred to as immutability, is a foundational aspect of His character. God's essence, promises, and decrees do not fluctuate with time or circumstance. Hebrews 13:8 declares, 'Jesus Christ is the same yesterday, today, and forever,' illustrating that Jesus, in His divine nature, remains constant and reliable. This means that the promises made by God are secure and will never change, providing believers with a firm foundation to rely on in a world marked by instability.