I agree. If you truly believe in diversity you should believe that even those who believe different from you should have their say. That is not we see from the left now.
Advocating discrimination against others regarding one of their characteristics is not an opinion or a belief: it is an abhorrent absurdity in the 21st century. Denying rights to other because of their gender, skin color, sexual orientation is an attack against someone's individuality.
Take DADT: gays can serve in the US military as long as they do not express their sexual orientation, as long as they hide what they are. Gays are good enough to be soldiers, to serve their country and potentially die for it but not good enough for them to have the same rights as others so they are second or third class citizens?
Where is the equality?
By the way, do not bother citing Voltaire and his supposed "defend the right to say it' citation, there is more than enough in Voltaire's work against religious intolerance and fanatisms from all sides to fill the forum.