If you're looking for a way to get the ones on your doorstep looking to save your soul, there's a simple and polite way to do that. Just say: "I don't accept the bible as the word of God."

That said, they tend to be spectacularly good at understanding the bible, so if that historical period is of interest to you, you might be in for a very interesting conversation (not in the "interesting times" sense - just interesting). Their entire religion is based on the bible being the literal word of god, so long as the meaning hasn't been lost in multiple translations - so they've spent a good bit of effort on figuring out what exactly the originals said. (Not an easy task, as paper only lasts so long and early Christians were, by and large, not literate.) Like I said, worth your time if you're interested in that period - once you get past the state of your soul.