Low-level lawyers have to take the cases their superiors assign. They don't get to choose or reject based on their religious beliefs.
Well I live in a small town in Texas, and yes - lawyers here can indeed reject cases based on their beliefs, religious or otherwise.
A firm could, I suppose require lawyers to take every case period, and around here that would relegate them to bottom of their class type marginally competent lawyers.
Maybe you deal with bottom feeding Dilbert managed firms. I don't bother with those, you get what you pay for.