Does God Exist? That is the principal question of theology.
There are several arguments attempted to prove the existence of God.
"The existence of God, as a First Cause, from the effects seen in the world" (James Boyce). One may look around and observe reality, energy, matter, etc. and conclude that there must be a cause for the reality, energy, matter, etc. a Supreme Being.
The ontological argument was developed by Anselm: "Something than which nothing greater can be thought so truly exists that it is not possible to think of it as not existing"
Also known as Intelligent Design, the argument assumes that for there to be order, there must be a creator. The alternative is often referred to as the "Tornado in the Junkyard"
From a literal viewpoint, in Genesis 1:1, the existence of God is assumed.