I made this [letter] very long, because I did not have the leisure to make it shorter. - Blaise Pascal

This art, which I call the art of persuading, and which, properly speaking, is simply the process of perfect methodical proofs, consists of three essential parts: of defining the terms of which we should avail ourselves by clear definitions, of proposing principles of evident axioms to prove the thing in question; and of always mentally substituting in the demonstrations the definition in the place of the thing defined.

We know the existence of the infinite without knowing its nature, because it too has extension but unlike us no limits.
But we do not know either the existence or the nature of God, because he has neither extension nor limits.

Reason's last step is the recognition that there are an infinite number of things which are beyond it.