(N.B. I got this by monkeying around with a proof from Brentano, dropping out some things and generalizing others. I introduced the symbol ‘P’ to explicitly avoid the perennial objection that cosmological arguments commit the fallacy of composition.)
1.) Whatever exists, when it exists, has a probability of 1, and is therefore necessary
2.) Whatever exists, exists when it does.
3.) Therefore, whatever exists is necessary.
4.) This necessity clearly includes all determinations, even accidental ones. It is necessary for Socrates to sit when he is sitting.
5a.) Let ‘P’ be physical existence, whether one considers it as various individuals, or as a whole universe, or any other object of physical science, e.g. a multiverse or alternate universe full of aliens that make our own universe.
5b.) It belongs to P it exists in itself that its determinations be possibly other, and are therefore not necessary. This is clearest in the accidental determinations of time, then of place and position. It also follows from P being a possible object of sensation.
6.) Therefore, though all existence is necessary, this does not belong to P as it exists in itself.
7.) Therefore, the existence of P is from another.
8.) But if there is something other than P, then it is supernatural and the cause of all P.
9.) And this all call a god.