rationalskepticism.org

There cannot be any causal explanation of why there is something rather than nothing, since the existence of a cause or causes presupposes the existence of something. So the only conceivable explanation is a modal explanation: There is something rather than nothing, because there must be something and there cannot be nothing.
The theistic explanation is such a modal explanation: There is something rather than nothing, because there is a god who is a necessary being.