If God didn't create everything, who did?
This argument is a result of a theist not being able to imagine that it was not in fact, a being that made the universe. The theist supposes that it was definitely a being that made the universe, when it may not have been. It is a fallacy that they are supposing that it could only have been a being and can be classified as a false dichotomy as a result.
It is important to realise that with a false dichotomy, the possibility of none of the above should be considered.