I don't affiliate myself with any of the political parties and every time I've taken a political party test I've ended up very near the middle. I agree with some Democrat issues and some Republican issues (and green party and libertarian) and have never felt comfortable siding with one side or the other.
That being said, I can never call myself Republican.
There are too many causes I support that get no support from major Republicans. Women's issues, climate change, the environment, gay rights, and energy are all things that I feel very passionate about and major Republicans don't agree with, don't believe in, don't support and won't pursue. In fact, some of these causes are openly mocked, called wrong or called unimportant.
Republicans think women's issues are silly girl complaints. We already work, we already vote, we already drive, we already hold major positions at major companies... what more do we want? Wanting better access to birth control just makes us sluts and wanting to keep abortion legal makes us all future murderers. If we're raped it's because we dressed provocatively, had been drinking, had flirted, had been out late at night, had not fought off hard enough, had basically asked for it, and if it was traumatic enough we won't get pregnant (or, if we get pregnant it was because we secretly enjoyed it and wanted a baby). Even though 95% of Americans have sex before they're married (if they get married at all), half the country believes sex should only be for procreating in between married couples, which means almost half the country are hypocrites.
Republicans don't believe climate change is real. The ones that do admit the science and data behind climate change is legitimate deny that we have anything to do with it. All those coal plants in the 40s that we shut down and cleaned up? If that were to happen today Republicans would lament all those coal jobs and ignore the improvements to the environment and human health. In fact, it kind of is happening today: Republicans are working hard to save the coal industry, claiming those few thousand jobs are critical to the health of the economy, while completely ignoring that people who work with coal all end up very sick, often with cancer. But those jobs, man, those jobs are all they got. (Which is true... people in coal mines don't know how to do anything else...)
Republicans think the environment is something we should care about only when times are good and we have the time and resources to devise ways of living that do not involve destroying the only place we can live. Since the planet will live far longer than any generation conceivable now, they kind of have a point. We will all die long before the planet starts to really hurt. So it kind of doesn't matter to us as a species. But for some generations it will matter, for the other groups of people and species that share out planet it already matters, and the things we're doing now will play a major role in the destruction of the environment.
Republicans think that giving gays more rights, namely the right to marry, is an "assault on the foundations of our society." To Republicans, gays are all that is wrong with our great country. Since God says their actions are punishable by death Republicans can't fathom why we'd want to condone their behavior. They've said we should round them up and put them in cages until they die off (since they can't reproduce the gays will stop existing). One even said the government should kill them all, an idea certain idealists took to heart. So at the very least, Republicans are saying they should just be happy that we aren't doing that to them and accept the separate-but-equal "registered domestic partnership" status, where we more or less arbitrarily decide whether or not that means a gay person's partner gets to be included on end of life decisions, get to visit in the hospital, and gets custody of the children.
Republicans do believe that we should be energy independent (or they're at least publicly saying so), but all that means is more drilling on our lands. Wind energy and solar energy are scams that don't create jobs and don't create energy, and since the environment isn't something they're concerned with they see no downside to drilling in Alaska or the Gulf (even though the poor Gulf is just barely hanging on as it is). Fuck the polar bears, the tuna, the shrimp, the moose, the ground water. We don't need them anyway.*
I'm a big supporter of all those things and say so publicly any chance I get (still waiting for my Human Rights Campaign equality sticker to come...), so identifying with a party that is vehemently against all those things means I can never side with that party. I don't see myself identifying with any of the other parties, either, but hell would pretty much have to freeze over before I called myself Republican.
PS- If I've made too many generalizations in this post and the links don't satisfy you, please leave a comment with some of your own links or other support for why I'm wrong. I'd really love to not believe that there are people in positions of such great power (one of whom is trying real hard to be the leader of the country), but I so far haven't heard anything to the contrary.
*Incidentally, during my research I clicked on a link that took me to the GOP.gov energy website and got a 404 error. Telling.