How do we know that the priesthood of Jesus is unchangeable?

The unchangeability of Jesus' priesthood is rooted in His divine nature and the perfection of His sacrificial work. In Hebrews 7, it is asserted that because Jesus is God and did not have the infirmities that characterized earthly priests, His priesthood is established by divine oath and not subject to change. His eternal intercession guarantees that believers are always represented before God, making His role as high priest eternally reliable. Jesus is described as 'the same yesterday, today, and forever,' reinforcing the certainty of His unchangeable position.