I'm no fan of religion, but the situation you described is true for pretty much all social hobbies. It's just one of the early steps in making friends. First you do stuff, then you meet people through that stuff forming acquaintances. Then you spend some time forming setting-specific friendships. It's fine to have lots of these, but the next step is to break out of that specific setting. Starting with immediate invitations to adjacent events ("Hey, want to grab dinner after our workout?", "Want to grab lunch after church?", "Hey, want to hit the bar after work?"). Once you have a habit of doing that, you can escalate to invitations to non-adjacent events. ("Want to go to a concert this weekend?"). Do that ever 1-2 months, and you've got a general friend.

The problem is you can't really just go to church to make friends without at all believing or supporting the rest of it. Similarly you couldn't go to a hobby group while entirely disliking the hobby, hoping to just get friends out of it and leave.