@Futiledemocracy Everything came into existence, but God did not. If He had come into existence He would be in need, and God is perfectLet's look at this and some related premises and see what conclusion logically follows...
(P1) A God would necessarily be a Perfect being
(P2) A Perfect being is Complete (or he would be in need)
(P3) God, if existing, could be the only Perfect and Complete being
(P4) Nothing can be against the Will of God
(P5) The universe exists
From (P1) and (P2) A Complete being cannot desire to create something, as that would imply a state of incompleteness and thus imperfection
Therefore, if God created the Cosmos it would have necessarily been against his Will, but from (P4) this is a contradiction
The Cosmos exists (from P5), therefore God cannot exist as it would be a contradiction.
From (P3) there are no other possibilities.
If there is no flaw in the premises or the logic then the conclusion necessarily follows - so which premise or deduction is incorrect and why?
Excerpts paraphrased from the Jainist philosophy of Acharya Jinasena, 9th century, Mahapurana (महापुराण) 4.16-31: If God is ever perfect and complete, how could the will to create have arisen in him? If, on the other hand, he is not perfect, he could no more create the universe than a potter could. How can an immaterial god create that which is material?