Just a note, all humor is at the expense of someone.
The chicken may not like everyone questioning his motives for crossing the road.
Absurd? Yes, but the point is simply, every joke is about someone or something. It will be offensive to someone or something if someone tries to find the offensive part.
Thus why comedians make fun of themselves first. Because if you can laugh at yourself, everything else you say MUST be ok.
And yes, there are LOTS of people who laugh about lgbt issues. I'm lesbian, and I'll laugh at a decent joke about gay marriage. Why? Because the whole point of humor is that someone IS the butt of the joke.
In this case? The mormon was NOT directly harmed. The joke wasn't ABOUT him, it was simply directed at him. It was a simply haha about well just because you think A is real, doesn't mean I don't think B is real.
She could have said many much worse jokes that would have questioned his faith, beliefs, or personal character. She did none of those things. She made a silly joke about unicorns.
This joke did not harm anyone in anyway (except those hardcore people who really hate unicorns apparently) and did what it was intended to.
Whether or not you like that she posted here, the fact is she did NOT bash religion in anyway. In fact, she simply used a joke to emphasize that not all people believe in what that person did. No harm, no foul. If it made her laugh, great, but if she hadn't laughed, would it be creating such drama?
If she had said instead that she pointed out to him that she might believe in unicorns, and were they in heaven too, but then went about her day WITHOUT laughing, then it would be ok? Because she wasn't "making the joke on him" but was asking a serious question?
Everyone is jumping onto the fact that there were 2 people in her group and 1 in his, therefore she MUST have been attacking him because of superiority in numbers. But the fact is she very well might have said the same thing alone, simply to get him not to say his speech. That her friend was there could very well just happen to be part of the story. Many posters here have said as much. That they SOLO would have said something similar or along the same tone. So the fact 2 people were involved is hardly reason to turn a joke into an attack.