"There are plenty of people who do stigmatize Christians and condemn them as such based on their personal histories."

That may be so, though I doubt that's a serious problem anywhere in the United States, where Christians are a powerful majority and regularly exercise their power to hurt minorities, especially LGBTQ people.

The topic at hand has nothing to do with criticizing Christians for being Christians and everything to do with criticizing the pervasive Christian tendency to exercise power to hurt LGBTQ people for being LGBTQ.

In case your comment about the college course was serious, btw, I was making a joke for effect. I doubt anyone believed I was positing that Morality 101 actually exists on college campuses. But I’m equally sure most people’s moral instincts inform them that exercising power to harm members of marginalized human minorities is wrong.