A book you've read that changed your view on something
Every book I read has the opportunity to change my view, but Heinlein's Time Enough for Love changed everything. It is the history of Lazarus Long, from his own point of view, but not. It covers many stories of his life, hints at his involvement in several of Heinlein's non-Lazarus novels, and explains in detail a moral system of love and existence that has stayed with me since the day I read it. Lazarus isn't about being nice to everyone, and he is not a pacifist, but he is unfailingly polite. He will be polite right up until someone pushes into his personal space, at which point he will politely warn you (if you are unarmed or stupid) or he will kill you (if you are armed, threatening, or known to be intelligent enough to be a real threat). He's surrounded by women despite being a curmudgeon, and I understand it. It's just one of those books that I read and re-read. I have owned about 8 copies over the past 20 years, and all have worn out. I read it at least once a year, and every time I read it, I learn something new not only about Lazarus, but about myself.
Your views on gay marriage
I think marriage is between you, your partner (or partners!) and your gods. That's that. So long as everyone is old enough to consent, and is going into it with eyes wide open, who cares who marries who? Two women? Sure! There are lots of stats out there right now showing that lesbian households with children have a 0% abuse rate. Two men? Why not? I have gay friends who are married and have children and their kids are the most polite, well brought up children I've met in ages. A man and a woman? I think that'd be okay, too. How about two men and three women? Yep, even that. After all, what matters is if you love each other and if you actually want to be bound together in the eyes of Deity as you see Deity.
Now... If you want to talk about contracts with the government, that's something else entirely. A contract is a contract. A "marriage contract" (or, as I call it for legal purposes, a wedding) is between a person or persons and the state or county in which that person lives. The state may or may not agree with a contract. That is the state's right, just as it is the right of the person or people involved to go to court to have their contract verified.
I do not believe the gubberment should have their fingers in the marriage pie. It isn't their business who I love or sleep with. On the other hand, weddings are important for those who want the security of tax shelters, health benefits, etc. I see no reason for The Man to be involved in that, as it is in most contracts at some level. Legally binding contracts are backed by the government to which we belong, as well as the laws of the land in which we live. That's a separate fight entirely. I am all for the government allowing weddings between more than two people - if nothing else, the national debt would probably go down as all the held-off poly peeps run out to get licenses. That, though, is a purely legal fight that someone is going to have to take to court. Me, I am just interested in the marriage part, personally.