If something is in motion, then it must be caused to be in motion by something outside of itself. So there is a first, unmoved mover. Therefore, God exists.
Some events cause other events.
If an event happens, then it must be caused by something outside of itself. So, there is a first, uncaused cause. Therefore God exists. So, if everything were contingent, nothing would exist now. So there exists a being who is not contingent.