My favorite comment to proselytizers...PROVE IT! Don't quote to me from an unverifiable old book...don't babble about how you don't need to ''prove'' the wind because you can feel it on your face, etc.
I have never found it to stop them. They just change direction or offer their version of "proof".
Yes...it always stumps them. They will then start quoting scripture....which as we know is all they have! They call it proof, I call it blind faith!