I took it to be more about the ethics of supporting the religious institution. For all the good they provide they also normalise a lot of hatred and anti-social values, even when they preach the opposite.
I don't know what to make of that - either I've been really lucky or the folks whose apriori stance is that there's no higher power and religion is bad, try to spin it that way.
But on the whole as I grew up and the conflict ended I still saw, for example, women's rights being denied, fast rights being denied and scientific fact (young earth, anti evolution) being denied by religious figures with political authority.
From what I see around the world via the media much of these same values are limiting the same rights in the US, and even more so in the Islamic world.
I've had many good experiences in churches myself and with being around religious people, but I'm also very aware of the experiences women and LGBTQIA+ people have in these environments and of how often church authorities have abused their power from covering up sexual abuse to exerting undue political influences or participating in what I would see as cultural genocides in the form of missionary colonialism.
I should also have mentioned that I was raised in the church, my mother was a Sunday School teacher and my grandgather operated a charity helping raise funds for churces in Nigeria. I'm far from an a priori athiest.
When you say it's not something you've experienced but you hear athiests talking about and then add that you wonder if the athiests are inherently biased, maybe ask yourself if you're not exhibiting a similar kind of bias by denying their concerns and their own lived experiences on the basis of a single data point.
Glad you're having a great experience, don't assume it's remotely representative.
Like if I went to a super active model airplane hobbyist meetup group filled with interesting kind people, so I could get the social benefits, but I actually believed model airplanes were silly and even more so that they don't actually exist