I am the new manager of a sub-team of 6 employees within a larger team of 65 employees. We work for a large Fortune 50 company in the US. One of my employees, "Helen", was previously refusing to work with another employee, "Mark". I had a conversation with Helen in which I made it clear that it's necessary for her to work with Mark at least for the next few months (until the current projects are completed). After that, Helen begrudingly started working with Mark, but now she regularly insults him to his face and makes negative comments about him to other employees.
I should say that Mark has no problems working with Helen or anyone else, nor do others have problems working with Mark.
It seems straightforward that I should tell Helen to cut out the insults and shit-talking. It's unprofessional and no one else in our department behaves like this. Helen has been in the workforce almost ten years, so she can't claim ignorance of workplace norms.
However, it's not so straightforward, because there is a religious freedom concern. Helen cited her religion (and went into some detail) as the reason she didn't work with Mark, and now she's citing her religion as her reason for insulting him and talking shit about him, both of which she acknowledged she does.
There is also a sexual orientation concern, because Mark is a homosexual. While he is very private about this, Helen found out somehow (I'm not sure how - I only know because Mark had to take a day off to take his husband for surgery a few months ago). I don't agree with his lifestyle choices, but Mark is a good employee with strong work ethic and integrity. That's all that matters to me as his manager. But Helen doesn't agree, and all of her insults and shit-talking center around Mark's sexual orientation.
In our state (US), it is illegal to discriminate on the basis of religious affiliation. Our internal company policies also ban discrimination on the basis of religion.
On the other hand, it's legal here to discriminate on the basis of sexual orientation. But our company policies ban discrimination on the basis of sexual orientation.
As a man of faith myself, I belong to a different denomination of Helen's religion, and I'm sympathetic to Helen's position on homosexuality as a whole. But I question if Helen is really allowed to first refuse to work with and later insult a homosexual employee simply because of her religion. That doesn't seem right. If Helen were not religious, or if her insults were related to some other subject matter, she would have had a meeting with HR by now.
How do I handle this conflict between Helen's religious freedom and Mark's sexual orientation?