Everything about our eternal life hinges upon the fact that God is incorruptible, unchangeable, and eternal in His essence. You can find enormous comfort just by meditating upon the eternity of God. Then you can rest in the certainty of His promises because He is an eternal God.
Consider the opening to Psalm 90.
Psa 90:1 A Prayer of Moses the man of God. Lord, thou hast been our dwelling place in all generations. Psa 90:2 Before the mountains were brought forth, or ever thou hadst formed the earth and the world, even from everlasting to everlasting, thou art God.
In verse 1, Moses mentions in his prayer that God has been Israel’s refuge in all generations. He points out the greatness of God’s power in forming the world, and then he highlights the boundlessness of His essence. “From everlasting to everlasting, thou art God,” he says. He never weakens. He has always been God. God neither began with the beginning of time, nor will He expire with the end of it. “Before the mountains were brought forth,” or before they were begotten, God always existed. He was before the world. He never began nor will He ever end. He is not a temporary but an eternal God. God is from eternity, “from everlasting.” He’ll endure throughout eternity, “to everlasting.” Only God Himself can claim that He is “from everlasting to everlasting.” No one else but God is eternal from everlasting to everlasting.
The fact that God is eternal is such an essential foundation to every promise and a great comfort to all of us, because if God had a beginning, He might also have an end. Thus, all of our hope hinges upon the fact that God will never end. Lo, David writes, “Thou art from everlasting” (Psalm 93:2). He says, “Blessed be God from everlasting to everlasting” (Psalm 41:13). Solomon tells us, “I was set up from everlasting” (Prov. 8:23). If his wisdom were from everlasting, then God Himself must be everlasting.
The idea of eternity can be difficult to fathom. We all know what time is but if we had to explain time, we might find that a bit more difficult. Likewise, we all know what eternity is, and yet, we cannot grasp it, although we can comprehend that there is an eternity. The same is true about God. We cannot comprehend the infinite essence of God, but we can comprehend that He is eternal.
Paul wrote of “His eternal power and Godhead” (Rom. 1:20). If He has an eternal, incorruptible power, then He must Himself be eternal. There can be no weakness in the nature of God because He is infinite.
Eternity is a perpetual duration. Eternity has neither beginning nor end. Time has both. Eternity is the duration of God’s very essence. Just as the essence of God cannot be contained, even the heavens of heavens cannot contain Him, so too, God’s essence cannot be limited by time. God is without beginning. “In the beginning” God created the Heaven and the Earth (Gen. 1:1). God was before the beginning of everything. Before the beginning of the creation, and the beginning of time, there could be nothing but eternity. I think it may have been Stephen Charnock who wrote, essentially, that “To be in time is to have a beginning. To be before all time is to never have a beginning.”
As He created life out of nothing, so He cannot be deprived by life of anything.
The years of God are as innumerable as His thoughts. David wrote in Psalm 40:5, “Many, O LORD my God, are thy wonderful works which thou hast done, and thy thoughts which are to us-ward: they cannot be reckoned up in order unto thee: if I would declare and speak of them, they are more than can be numbered.”
Plus, He never forgets, and He is eternal! This means that His wisdom is infinite just as the number of His thoughts are infinite because He is infinite.
We, on the other hand, we live. We grow. We become wiser (hopefully). We gain things. We lose things. Every day, we get older. Weird (and sometimes sad) things happen to our bodies. But God never changes. God never weakens. God never grows old. He is the same as He was before He ever created us. He is always the same. He is always unchangingly holy and incorruptibly perfect in all His infiniteness. All of His perfections are perfect every moment throughout eternity. We may say, “well, I used to be that way.” Or “I hope to be become this way.” God says, “I am.” He is what He always was, and He always will be what He is.
We find in Exod. 3:14, “And God said unto Moses, I am that I am; thus shalt thou say to the children of Israel, ‘I Am hath sent me unto you.’” This is the name by which God can be distinguished from all creatures. I am that I am. His essence has never changed. I am that I am. I am the only being, the root of all beings. I am eternal, perfect, unchangeable. I am always and immutably the same. I am that I am. I am an infinite life and an infinite giver of life. I am the same in every moment I exist, and I will be the same in all the moments to come.
How could we rest in peace if God were not eternal?