Why It All Began

The poet is more of a cosmologist in the 90th Psalm. He envisions a time before the earth  existed, before mountains came forth, and concludes that God made something from nothing. There is  no big bang here, but a creation, or perhaps a transition, is called for. The immensity of time is called for "Even from everlasting to everlasting, Thou art God."

This is rare thinking in a time when the existing world was considered to be permanent and eternal. The poet also wrestles with time, unlimited time that God has at His disposal.  God chooses; He creates! That's his conclusion to the question of why we exist. 

Scientists at the Hadron Collider are trying to fathom how something arose out of nothing. But they cannot begin to answer the question of why that happened. Leave that to the poet, the psalmist. It is imagination stretched to the utmost.