The Eternality of God refers to his timeless nature. God had no beginning, and will have no end.
This is one of the foundational beliefs of Christianity. If God is not eternal, then eternal life is not His to give to anyone. Also if God had a beginning He too would have to have a creator, at which point he is not the one true God. Without the eternality of God, Christianity is futile.
God's eternal Nature is very important to us because it ensures that God will always be there for us. Whenever we need Him, no matter when we are troubled, our eternal God will always be there for us.
There are numerous references throughout scripture about God's eternal nature.
- Isaiah 57:15, "For thus says the One who is high and lifted up, who inhabits eternity..."
- 1 Timothy 1:17, "To the King of ages, immortal, invisible, the only God, be honor and glory forever and ever. Amen."
- Attributes of God: How Old Is God?, or the Eternity of God (MP3), by S. Lewis Johnson