Hi
I consider myself to be a somewhat religious person, however...
It is OK for you to bash religion all you want in therapy. It wouldn't be therapeutic if you couldn't.
My point is that you are there to talk about whatever you need to. Unless you are personally attacking the therapist, they will be able to handle it. Yhe things we come up with reasons not to talk about are probably the things that we need to get out the most urgently.