Wow -- missed this comment! I do tend to give various evidential reasons, but when discussing this topic at all (like Nornagest suggests), there's always an out. PoE, why religious diversity happens to be so geographical, etc. There's always an answer.

When I suggested to a theology professor (that a friend suggested I speak to) that I found it odd that if there was one true god, the world wouldn't have figured it out by now, he responded in a completely unsurprised way and simply said that Jesus never foretold that Christianity would be a world-wide religion.

In fact, he said, the picture of the world is exactly how he would have expected. Yeah right. Anyway, there does tend to be a response to everything.

Re. god not showing up... he won't override your free will, or he does but you need "eyes of faith" to see it, or it's because your heart is hardened.

Perhaps this reply has helped me understand why the best mode of response is just not to engage. As long as there's nothing that would change a believer's mind... there's nothing that would change a believer's mind.

And if there is something that will... it probably won't be from me, or at least not in direct conversation.

The ticket is probably to say something like you've said, but then simply "broken record" the rest of the conversation with, "My research has convinced me. I'm still open, but I believe my current stance to be rationally reached and based on a wide range of currently available evidence."