As allies go, I am not the greatest.
I am inexperienced. I don't know all the facts, figures and arguments necessary to shoot down bigoted, ignorant views. Like that one guy in the pub who "has a black friend", I don't have a plethora of close friends who happen to be marginalised in ways I am not.
Being an ally is scary because you can get stuff wrong. In fact, you're going to get stuff wrong. As a straight, cis woman I don't know the experience of the gay, bi, trans or non-binary humans I share the world with. And as a result how I imagine, and therefore defend, that experience may miss the mark.
But an argument I feel able to give, and that I hope is of value, is the argument for kindness.
Kindness is something I value, something I think I can argue for. I don't know the all of the arguments to persuade someone to support marriage equality, or to change how they define gender. If I did, I doubt I'd have the skill to convey those arguments convincingly. But I know that to deny people the validation of their experience or rights enjoyed by other people is unkind, even cruel.
The people who show this unkindness would have nothing to gain from it. Does denying same sex couples marriage equality stop straight couples from getting married? No. Does barring trans women for female spaces make being a woman in a patriarchal society any easier? No. Just as telling an immigrant to stop taking British jobs won't stop you being unemployed, these acts of unkindness do nothing but harm people who just want to live their lives.
The American Declaration of Independence, written by Thomas Jefferson, states that our inalienable rights include "life, liberty and the pursuit of happiness". I would argue that a right to pursue happiness infers a right not to have that pursuit impeded. Hatred, bigotry, intolerance; these things impede the people they target from finding happiness. And that's not ok.