Something I've been thinking about a lot lately, and had considered writing a thread about, is, What Does Mental Illness Look Like Online?
I've often wondered how many of the people here who just will not let go of their rants, which often have nothing to do with anything else discussed, are mentally ill. I've been on CC since 2009 and have seen a few things... I remember one member (who's not here anymore) who used to go on wild rants in the Bible Discussion chat room. I don't mean this in a judgmental way, but from his appearance the the condition of his surroundings on his webcam, this was a person who invested very little time in personal hygiene, cleanliness, or organization.
All the clues seemed to point to a situation in which this person had very little, if any, regular interaction with people in real life. Rather, it seems he devoted all his time to his own method of Bible study... and then trying to convert others to his superior way of thinking.
I could be wrong, but I personally believe that people who purposely limit their contact with real people usually lose contact with reality.
The reason I think about such things isn't to try to condemn such people, but just that it can help us use a bit of discernment. For instance, if I suspect this is the case with a person who is always ranting and condemning, I don't see a point in arguing with them because the rational part that could have a productive discussion is either suppressed or missing altogether.
In that case, I know my time is better spent trying to build a relationship/friendship/Christian fellowship with someone else and just praying for the said person who refuses to say anything positive or listen to what anyone else has to say.