Full Idea
There are three proofs of the existence of God: the physico-theological, the cosmological, and the ontological. There are no more of them, and there also cannot be any more.
Gist of Idea
Only three proofs of God: the physico-theological (evidence), the cosmological (existence), the ontological (a priori)
Source
Immanuel Kant (Critique of Pure Reason [1781], B619/A591)
Book Reference
Kant,Immanuel: 'Critique of Pure Reason', ed/tr. Guyer,P /Wood,A W [CUO 1998], p.563
A Reaction
It is hard to deny this, though the 'physico-theological' group may be a sizeable family. The immediate difficulty may be that physical evidence supports something less than God, the cosmological is just speculation, and a priori proofs won't work.