(1) Contingent things exist.
(2) Every contigent thing has a time at which it fails to exist.
(3) If everything were contigent, there would be a time at which nothing exists, an "empty" time.
(4) Such an empty time would have been in the past.
(5) If the world were empty at some time, it would be empty forever after that.
(6) Therefore, if everything were contigent, nothing would exist now.
(7) But things exist now.
(8) Therefore, there must be a non-contigent being.
So, G-D exists.