I'm sorry you feel that way. You should know the worst abusers of this sub are Christian, not Atheists. This sub has been a bastion of theological discourse about Christianity for some time. Pretty uniquely it also contains a great many different sects for Christianity. For some people this is the first time Christians who disagree with them have a significant voice. They're still Christians but their faith can look radically different due to different interpretations of the Bible and Christianity. This upsets some people, it seems unthinkable that a christian could believe such different things than them. Thinking that that so called Christian must be wrong is usually where they end up. This is incorrect because it betrays a total misunderstanding of how diverse Christianity is, even within orthodoxy.

Successful posters learn how to present their views with the understanding some people may disagree and even that people that disagree have well founded reasons too. These people get upvoted. People that post without respect to the great variety of Christian traditions, people who make absolute truth claims and people who are insensitive to how things sound even if what they say is correct get downvoted.

Perhaps it is a poor environment for one who doesn't like hearing the other few thousand Christian denominations but for those who enjoy the variety, there is nothing like it.

In that particular thread people were careless about the effect their words have on people. Telling someone who has recently fallen from Christ about the very gender issues that drove them away is not productive even if it is correct in your view. Telling them all the good reasons why homosexuality is a sin actively harms the christian cause by pushing people further from us. There is a time and a place for everything. That was not it. The lack of consideration for the fact that telling "truth" improperly or tactless is useless was ignored by some and they got downvoted or removed because of the harm and distress it caused.

Does what I've said here make sense? The subreddit really is something else and I'd strongly encourage you stay for the perspective it brings.