There are things that are knowable and things that aren't. The cause of the beginning of the universe is one of the things that isn't. No one has any evidence about anything having to do with it, nor is it possible for them to have any.

If we're going to make guesses, I rather like the idea that there was no beginning and no cause. Everything always was (is). It makes as much sense as any other explanation and has grandeur and mystery to boot.