If I may refine it further, the issue is that the universe must
have a cause because it has a beginning. The Big Bang is a theory
to explain the phenomena of the expansion of the universe from a
singularity event in the distant past. But this initial singularity
event itself begs a cause, because "bangs" don't just happen
without a cause.
The argument then is that either God made the universe, or the
universe made itself, or nothing made the universe. I think the
last two options are not very attractive at all. But perhaps
someone might have another view to avoid the God alternative?
One of the new ideas to avoid having to deal with a divine cause
for the universe is to invoke the idea of multiverses which some
have claimed to have mathematical and theoretical support. In other
words, there are millions or perhaps billions of universes out
there and our universe just happened to be the lucky one to contain
life. The analogy usually given is that of the lottery, that even
though it is highly improbable someone will win the lottery.
But then here's where I think the double standard comes into
play. Atheists would argue that even though it is so improbable yet
it must have been so that it happened at least once, since our
universe exists, otherwise we won't be here to talk about it. Yet
they would deny that similar argument for God, saying that God is
so improbable that therefore He does not exist. So on one hand the
improbable multiverse scenario means it happened, but the
improbable God scenario means no God.