My son told me that last Saturday in Torah study a participant made a stupid and ignorant remark about Christianity. My son didn’t say what it was, only that he considered walking out, but did not.
My immediate response was that if he were to leave he should first wait to see if any of the other participants spoke out. We talked about that a little until we realized that he should have spoken up immediately himself. The hope would be that the speaker would realize their mistake and withdraw the remark or engage in discussion and then withdraw the remark.
In the absence of that we would expect that one, if not some, if not all of the participants would support the objection.
If none did they would all be complicit and we would know more about them than we wanted to. That would be the time to leave!