I know some of you are thinking "oh, no, is she really going to open this can of worms?" Yes, I will, because it's about basic rights and if your basic rights were being denied, you'd want someone to stand with you too.
See, I'm fortunate. I'm female and I'm attracted to males and no one really has a problem with that. I'm fortunate that the right to marry whom I will (assuming whom I will also wants me) has never been denied me. Now, I've dated men of darker skin tones than I, one of them wasn't even born in this country, and there was a time when that would have been scandalous. But it's not so anymore, the laws changed and there is no problem with the mixing of skin colors in the eyes of the law. There is still a problem in the eyes of some people, and I experienced plenty of that, but we could have been married if we wanted to be. Things change. They have in the past and we can only hope they will continue to do so.
I'm pagan, I don't hide this. I'm an Eclectic Hermetic Wiccan Quaker. (There really isn't a word for what I believe, which is kinda cool when you get right down to it.) The main and supreme tenet of my belief is a part of the Wiccan Rede, "An it harm none, do what ye will." Harm none. Simple. Yes, it is impossible to go through life never harming another living thing, but it is possible to go through life without intent to harm another living thing, and intent is everything in my faith.
So, I support marriage equality. Why? Because it doesn't hurt anybody. Two consenting adults who want to share their lives and become their own family unit does not hurt me, and it does not hurt you, and it does not hurt the Earth, it does not hurt the children (http://pediatrics.aappublications.org/content/early/2013/03/18/peds.2013-0376). That's the truth. Simple.
The primary argument against marriage equality often sites the Bible as the reason. I'm not going to go into why I feel the Bible argument is wrong, but I will say the Bible argument is irrelevant. The United States of America is not a theocracy. If your god does not allow same-sex marriage, that's fine, just remember that your god's laws do not apply to everyone. And nor should they. My god's laws do not apply to everyone either. That is why I wear a veil and you may not and that's ok. Your beliefs are yours and no one is asking you to change them. What we are asking is that you keep them out of the federal laws, those are the laws that everyone must follow regardless of personal belief. That's really what it comes down to. If your dogma believes it's wrong, just don't do it. I don't understand why you think everyone has to follow your laws.
The other side of that is that the government can't make a properly registered and recognized church do anything. They can't make a church authority perform a same-sex marriage if such a thing disagrees with that church's dogma. Anyone trying to make that happen is not on the right path.
The bottom line: Live, let live, don't discriminate, and if it's not hurting you or someone else, it's not a battle worth fighting.