The strongest argument for a god is that the idea that the material universe would come into existence without an external cause violates every known law of said universe. The problem for most theists is that it’s a long way from this argument to belief in a specific revealed creed.
I’ve never found this notably more convincing than any of the others. By the same logic, God ought to have had a creator, and his creator a creator, and that creator a creator, and so on and so on forever. If you’re going to refuse to accept this infinite regression, why can only God be the prime mover, and not, say, the Big Bang?
The argument assumes that it’s in a god’s nature to not need a creator. Which may not be supported by any empirical observation, but it’s easier to wrap your head around than the idea that all the matter in the universe spontaneously came into existence, all at the same time, for no reason.
