I wouldn’t describe many of them as rationalists, particularly, but it seems that according to lesswrong doctrine, they are above the sanity waterline while my first friend group is below.

Woah there! I never signed up to any doctrine like that! Where is that one written down? (So that I can reject it explicitly in the right context!)

For a start, a lot of those non-believers that you know I would almost certainly consider below the sanity waterline. And some of your Christian friends probably come in above. My immediate family members, for example, are some of the sanest people I know yet most of them remain sincere Christians. Sane enough that I mean no insult at all to any of us when I declare them more sane than the average lesswrong user. I don't judge people as below the sanity line based off them believing one stupid thing. I mean, I don't outright consider Eliezer to be below the sanity water line just because he believes (or signals believing for some practical purpose) really dumb stuff here and there.