Could God exist if nobody else did? No. That’s why gods are very avid for worshipers. If there is nobody to worship them, there are no gods. There are as many gods as there are people thinking about God. When Mrs. Mulligan and the Pope are thinking about God, it is not the same God.
In choosing your god, you choose your way of looking at the universe. There are plenty of Gods. Choose yours.
The god you worship is the god you deserve.
–Joseph Campbell, A Joseph Campbell Companion