The Mormon Church is an illegal PAC. They should be taxed, minimally.
I think so many of these churches should be taxed to be honest. I mean, the megachurches partake in politics and if you do that then you should lose whatever exemption you have in my opinion.
I'm having trouble finding stuff about this specifically but:
The linked source is the Savage Love podcast with Dan Savage and it seems like he's been alongside the LGBT community but I understand what you mean with the tithing going to an organization like the Mormon Church.