Otherwise you’ll end up in a social corner filled with bitterness

This is a standard Internet phenomenon (I generalize) called a Sneer Club, i.e. people who enjoy getting together and picking on designated targets. Sneer Clubs (I expect) attract people with high Dark Triad characteristics, which is (I suspect) where Asshole Internet Atheists come from - if you get a club together for the purpose of sneering at religious people, it doesn't matter that God doesn't actually exist, the club attracts psychologically f'd-up people. Bullies, in a word, people who are powerfully reinforced by getting in what feels like good hits on Designated Targets, in the company of others doing the same and congratulating each other on it.