The thing that makes civil rights a big deal is that it affects people.

If you are against gay marriage or interracial marriage, that's a statement about how you feel about people. Gun control is a lot less about how you feel about people.

I think for me, and many others, gay marriage seems like such an obvious thing that I really question the ethics of one who opposes it. There is probably no other major issue in the US that I think is as obvious -- not immigration, abortion, climate change, gun control, taxes, health care, Russia, torture, etc...