Who knows? But why not give the same skepticism to the idea of "there is no God"?
Back up one step and ask, "Where did the universe come from?" Insert your answer, "Who knows?"
You're adding a step that's not needed.
From our perspective - you are correct - we don't know. But as I posited previously, the idea of a creative mind is scoffed at while any "natural" explanation of our universe (parallel universes, expansion, contraction, etc.) is excepted as simply one more plausible explanation.
Please explain to me why otherwise rational individuals will except the wildest explanation for the origin of the universe, and yet reject out of hand the most obvious: that from our own observation - causeless effects are not rational.
Everything we see screams out "created!". And yet the idea of a creator is the stuff of fairy tails.
Where in your experience have you come across the magic of something coming from nothing?