For many who believe in God . . . he stands outside of the universe, outside matter, outside time, outside of “being” as such.
-SBF
Surely you'd agree this is a case of Special Pleading. When we talk about existence we are necessarily describing something that is both local and temporal. To say that something "existed no-where for zero seconds" would be the same thing as describing something that doesn't exist.
If Theist want to put forth the proposition that God "exists" outside of space and time then they need to first demonstrate that such a thing is possible - AND THEN they can use that as an explanation. Not before.