Why do you think atheists pay so much attention to religion?

[Rev. Rye]

It's really hard to talk about disbelief. "you don't believe either....cool" would be the gist of the conversation.
People don't usually talk about what they don't believe in, but rather what they DO believe in.
In the western world, Xianity is the dominant "In your face" religion and is ~2B strong so it's what tends to be the focus
of debate and rancor for many ex-xians.

In addition, not only is it hard to talk about disbelief, the problematic nature of some belief systems does make excellent conversation, at least until it starts to get ugly.