Those things don't go hand in hand. you can be a Christian and have the common sense to see that evolution is real and gays deserve equal rights.
as a Christian myself, I'd have to half-agree, half-disagree with you.
Evolution is only true certainly true in a sense. There are two different types, macro and micro. Micro has to do with natural selection and a species' ability to adapt over time. Macro, however, is the idea that enough micro-evolution can occur that one species actually becomes an entirely different species. Micro is easily provable by science. What science then tries to do is prove macro using micro, and it simply doesn't work. The theories of evolution have holes all over the place, and most of those holes are called "missing links." These missing links are the supposed in between species that show how one involved into another, but as far as geology and paleontology and such can tell us thus far, no missing links actually exist. Its all speculative.
As for gay rights, I do personally believe gay people (in a worldly sense) deserve to do whatever they want to do. However, the Bible is clear that homosexuality is as evil a sin as lying, murder, looking up porn, gossiping, etc, in that all of those sins are infinitely offensive to God. So as someone who follows the Bible, I cannot support homosexuality. I would also consider it wrong to force anyone to follow the Bible against their will. With both of those sides in mind, I don't think I as a Christian can rightly vote for gay rights nor vote against them. This isn't a widely heralded view though, and I stand in a smaller group of anti-theocratic believers. The only places where I think I am allowed to deal with homosexuality is when brothers and sisters who claim Christianity and say they believe in the Bible still choose to pursue a homosexual lifestyle. But I'm not going to deal with them using the law, but instead by trying to just talk with them and love them on a person-to-person basis.