This is agnostic.com, so maybe we could take the predominant atheist position as read, and not talk about it so much? Just a thought.
There's a simple solution for you. On the homepage, you can select what categories you want to see in your feed (click on settings icon between Trend and Search). If it bothers you so much to see people discussing topics related to religion don't visit that category. Just a thought.
A lot of unbelievers here are confused / conflicted about the Great Questions and want to discuss them to refine their thinking. Not everyone has completely thought everything through that they feel a need to.
A lot of unbelievers here are deconverts still processing the harms of their faith, and the loss of their faith (alienation from community and belonging). They should be able to discuss / share / vent as needed.
A lot of unbelievers here are anti-theist, even activist anti-theists, and that is their right, and their voice shouldn't be silenced either.
A lot of unbelievers here are ignositics or burned out on such discussions and therefore indifferent. They have a recourse: start and participate in topics and groups of their choosing, avoid categories and groups that focus on things they're turned off by or not interested in.
When you think about it though, if you're not interested in [anti]theism or [a]theism or [a]gnosticism then the set of things to talk about doesn't really require a site specifically for atheists and agnostics; you can go find something like MakeAirplanesFromBalsaWood.com or StampCollecting.com, where you'll only have to avoid the very occasional religious or political nutter.
I find there are enough groups and other like minded people that I am able to enjoy this site and not be too concerned about those who have been damaged by religion and at times need to rant and vent.
I would suggest checking out the list of groups within this site.