I know that's the same argument the professor was making, essentially, but forget the specific details of this case for the moment and look at it in the abstrac

I know that's the same argument the professor was making, essentially, but forget the specific details of this case for the moment and look at it in the abstract. You -- and he -- are essentially arguing that the legal right to religious freedom carries an ancillary right to be actively insulting to others who are required to interact with you in entirely non-religious contexts. That strikes me as a hell of a reach. If you genuinely feel that your religion obligates you to be an asshole to people who you believe are violating its tenets, then maybe the onus should be on you to not choose a career that may put you in regular contact with those people.