Fundamentalists in my experience genuinely fear information that hasn't been vetted and approved by their handlers. I know that I used to, without realizing that I was being subjected to what was really a form of mind control. It's so much a part of their everyday existence that it doesn't seem odd to them. It is a literally from-the-cradle indoctrination -- lean not unto your own understanding or mere human wisdom, everything you need is in the Bible or in our exegesis thereof.

As such, as soon as you start to talk about anything unfamiliar to them, they will generally become anxious about it, which causes them to revert to the closest match in their mental library of received teachings about the topic. The god talk is largely formulaic, to direct it away from alien topics and sources of information, and to put you on notice that they will not listen to information that is not "Biblical".

To the fundamentalist mind you are a source of "doctrines of demons", a sort of direct link to the pit of hell. Of course, some fundies are worse than others in this regard, but even the relatively mild and superficially cultured fundamentalism I grew up with, was extremely anti-intellectual, distrustful of anything coming from a secular source, skeptical of science whenever its truth claims conflict with dogma, etc.

There's really not much you can do about it. If you meet someone who is receptive, which you will now and then (usually when they're separated from their herd), you might be able to have at least a skim-the-surface conversation where they will actually try to understand what you're saying, but for the most part ... fundamentalists are lost to rational discourse and the sooner you understand that, the lower your blood pressure will be.

I usually expound on their entire false premise that faith (belief without evidence) is a method of establishing factual (testable) understanding.

If they take offense, I don't feel bad when I explain that I prefer reality based on facts as apposed to their understanding of the world based on fantasy: what you would like to believe without any foundation in testable facts or reality.

Sheeple Suck! Without them we could actually solve problems instead of treating conditions of belief, we could have sanity in the masses instead of a bunch of asses.