Interesting link from Facebook. While I am not sure that proselytizing is the right way to go, a friend did pose an interesting question once to a person who was a young earth creationist: 100% sure that the Bible was the only source for truth in the world and that science had no place in the public sphere.
“Do you take asprin?” he asked.
“Yes, of course” the person replied.
“Well is asprin in the Bible?”
“So if it isn’t in the Bible, why do you think it will work?”
“Well, it says so on the bottle, and it makes my headaches go away.”