I can't upvote this point enough.
And more worryingly, with the Christians I have spoken to, those who are more consistent in their beliefs and actually update the rest of their beliefs on them (and don't just have "Christianity" as a little disconnected bubble in their beliefs) are overwhelmingly in this category, and those who believe that most Christians will go to heaven usually haven't thought very hard about the issue.
C.S. Lewis thought most everyone was going to Heaven and thought very hard about the issue. (The Great Divorce is brief, engagingly written, an allegory of nearly universalism, and a nice typology of some sins).
r/Fitness does a weekly "Moronic Monday", a judgment-free thread where people can ask questions that they would ordinarily feel embarrassed for not knowing the answer to. I thought this seemed like a useful thing to have here - after all, the concepts discussed on LessWrong are probably at least a little harder to grasp than those of weightlifting. Plus, I have a few stupid questions of my own, so it doesn't seem unreasonable that other people might as well.