I am one of those who participated in this community for several months without joining. I left comments and occasionally was treated rudely by a hubber. Not because my comment was rude, but because they felt I was not good enough. I was made to feel that if I did not join to comment, I was a bad person. But the people that we get our income from are driven to us by Google, so they should be welcomed.
That said, a hubber that does not write and just comments may have been made to feel the same way that I was. So they joined to comment.
Sometimes a person who is really looking for God, denies him the most vehemently. They are trying to find someone who can convince them that there is a God. Perhaps this person is one of those. If they are, treating them with love and respect and in a Jesus-like manner could be the thing that convinces them. How would you feel if treating someone in a non-Christian manner kept someone from finding God? The only thing to do, is to treat them with love and respect. Do not encourage his rudeness, but do not discourage them seeking either.