It isn’t really about edginess. People tend to continue believing in whatever religious preference (or none) they have unless something convinces them otherwise in whatever direction.
To an atheist’s point of view, it legitimately doesn’t make sense why someone would be religious when what they see is nonsense. It is a genuine confusion and not necessarily meant to be rude.
This isn’t just an atheist thing that happens, religious people can often not understand why someone would ever choose anything other than their religion. It doesn’t make sense to them either.
There is a common circle jerk for sure. Humans gonna human, it happens everywhere. However the question was honest if a bit rude sounding.