God has no beginning or end
Everything we know has a history. Mountains rise, kingdoms fall, and even the longest human life is brief. God is different. Moses describes God as existing before the mountains and before the earth was formed, with no starting point behind him and no finish ahead of him (Psalm 90:2).
This doesn't mean God has simply lived for a very, very long time. It means he is not a created being at all. Genesis begins with God already present and acting to create the heavens and the earth (Genesis 1:1). He does not depend on the universe for life, purpose, or existence.
Before the mountains were brought forth, or ever thou hadst formed the earth and the world, even from everlasting to everlasting, thou art God.
God is not worn down by time
Time can drain us. We forget, weaken, change our minds, and run out of strength. Isaiah tells weary people that the everlasting God does not grow faint or weary (Isaiah 40:28). His wisdom is not exhausted by the complexity of your life.
God's eternity also helps explain why his faithfulness can be trusted. James says there is no shifting change in the Father of lights (James 1:17). That does not make God distant or cold. It means his goodness is steady, even when your circumstances are anything but.
Hast thou not known? hast thou not heard, that the everlasting God, the Lord, the Creator of the ends of the earth, fainteth not, neither is weary? there is no searching of his understanding.
Jesus shares God's eternal life
Christians understand God's eternity to include the Son. John's Gospel begins by placing the Word, who is later identified as Jesus, with God before creation, and says that all created things came through him (John 1:1-3). Jesus is not presented as one more creature inside the world he made.
The New Testament also says that Jesus Christ remains the same through every age (Hebrews 13:8). This is a comfort when reading the stories of Jesus. The one who welcomed the weary, forgave sinners, and called people to trust him is not confined to the past.
In the beginning was the Word, and the Word was with God, and the Word was God.
Why God's eternity matters today
God's eternal life does not solve every question about suffering, waiting, or the future. But it gives a solid place to stand. Your life matters to the God who sees the whole sweep of history, while also knowing each person personally.
Moses contrasts God's enduring life with the shortness of ours, then asks God to teach his people to use their days wisely (Psalm 90:12). God's eternity is not meant to make ordinary life feel small. It can help us receive today as a gift, seek what is lasting, and place our hopes in the One who will not disappear.