“But You are the same, And Your years will not come to an end.” (Psalm 102:27, NASB95)

In contrast to man, God is the same. [Hebrew: “You are he”] Man changes, God never changes.  Man’s years will come to an end, God is eternal.  Man grows old and dies, God has no age and is not subject to the vagaries of old age and death. Man is temporal [in his physical body], God is eternal.

Surely the writer to Hebrews had this psalm in mind when he points out that:

Jesus Christ is the same yesterday and today and forever.” (Hebrews 13:8, NASB95)

The only way that Jesus Christ could be the same was if he was part of the Godhead that never changes.  In the same way that God does not change, Jesus the Messiah does not change either because he himself is God.

This is a humbling truth.  There is a stark contrast between Man and God.  Man in his sinfulness does not like to acknowledge or admit it, but it is true nonetheless.

When Christ in past years did gird himself with mortal clay, the essence of his divinity was not changed; flesh did not become God, nor did God become flesh by a real actual change of nature; the two were united in hypostatical union, but the Godhead was still the same. It was the same when he was a babe in the manger, as it was when he stretched the curtains of heaven; it was the same God that hung upon the cross, and whose blood flowed down in a purple river, the self-same God that holds the world upon his everlasting shoulders, and bears in his hands the keys of death and hell. He never has been changed in his essence, not even by his incarnation; he remains everlastingly, eternally, the one unchanging God, the Father of lights, with whom there is no variableness, neither the shadow of a change. – Charles Spurgeon; Jan 7, 1855 sermon