I would think the question of this thread was asked back during the heavy proselytizing in the first millenium by many a pagan. I almost believe that something happened to our brain wiring that the concept of one God seems only natural to many, while the concept of many Gods seems silly to many.
The Hebrews were laughed at for believing in one God.
Plus, many people that believe in a God think it is silly to believe that no God exists.
It may be futile to argue the whole God concept, since it may have to do with different wiring in our brains?
In general, Judaism views the existence of God as a necessary prerequisite for the existence of the universe.
The existence of the universe is sufficient proof of the existence of God.
One of the primary expressions of Jewish faith, recited twice daily in prayer, is the Shema, which begins
"Hear, Israel: The Lord is our God, The Lord is ONE."