Before we begin:
1) Yes, the title is deliberately provocative.
2) No, I don't actually hate all Christians. My eldest sister, for example, is fairly devout by NZ standards, and she's awesome. Similarly there are entire ministries that seem to have actually read the Bible and are openly accepting of all people and perfectly willing to not try to convert you in every conversation.
3) It might be more accurate to say I hate hateful people, or bigots, or whatever. But if I say that, it's very easy for people to ignore it. "Well, I'm not hateful," they think, and go on with their day. If someone ties in a group they identify with, they have to actually pay attention, even if they then dismiss it entirely anyway. And the hate is so inextricably tied up with Christian tradition that there is still accuracy in this stance.
4) Before you go further, Google "No True Scotsmen". Here, I'll even do it for you. I will get into this further below, but it will help if you have a basic idea of the concept.
5) I'm aware that other religions hate gays too. Mostly Abrahamic ones. However Christianity holds a hell of a lot more influence over the Western world where most people reading this live, as well as a lot of the rest of the world as well. There are a hell of a lot of Muslims, but on a global level, I believe that Christianity still "outranks" Islam when you look at power and influence, even if both of them have their good and bad parts.
6) I am not a hypocrite for blasting Christians for their hate. Why? Because there's a huge difference between hating a minority group that's minding its own business and hating a dominant group for oppressing you. Don't try to argue this point with me. Anyone who can't see this is either intellectually dishonest or stupid as fuck.
Now that we have that out of the way...
Christianity is the dominant group in Western society. Yes, it is. You may not notice if you're Christian, you may not even notice if you're not, but to someone like me who believes religion is personal and has a completely different belief structure, it is awkward as hell to sit through a Christian funeral service (as far as I can tell this means all of them, unless they're specifically something else), wedding (almost as much so) or prayer in general (every day in Parliament, for starters). The problem is that Christianity is so much a part of Western culture that it's difficult to point to parts of it. It's everywhere. It's our holidays, our calendars, our laws, our social codes, our charities (for a fun time, ask me about the Salvation Army - not specifically the NZ one, it's much worse in eg the US), our media, our stereotypes, our view of history, our discussions, our art, our literature. This isn't always a bad thing, though I'm not sure I'd categorise any of it as good either. It just is. Contrary to what some people think, I'm confident we'd have fair and decent moral codes and laws without Christianity, or even without religion at all, so I don't buy into the argument that Christianity props up the justice system. But it bothers me that everyone is expected to know particular Bible stories, but many New Zealanders only have the vaguest pictures of Maori folklore and oral history.
That's only a minor annoyance though. The real bugbear is [one of] the dark side[s] of Christian morality - its attitude towards LGBT people. I'm queer. I'm not sure I'm specifically trans, but I'm sure as hell not gender-normative. And Christianity hates that. Just this morning I had a Christian guy telling me the names of some books I should read and wishing me good luck on some imaginary quest to somehow become not gay, which is still infinitely better than ex-gay therapy, something that all reputable psychiatrists agree is pretty fucking harmful. It doesn't matter, inherently, whether queerness is nature or nurture, because everything we've learned about it indicates that you can't just choose to stop being gay. (I do think sexuality is in some ways fluid, but that's still not the same thing, which I might get into another time. The tangent would be too long for today.) This guy didn't even think he was doing anything wrong. He thought he was helping me. He probably would have said he was doing it out of neighbourly love - something that couldn't possibly be good for me, would almost certainly devastate the stable mental state I've worked incredibly hard for, and might well kill me.
Many Christians would tell me - and have done - that the bigots are not really Christian. This is where No True Scotsman comes in. Telling me this doesn't help me. It doesn't fix anything. All it does is make you feel better, because it removes your culpability by pushing the villain away from anything you're associated with. Unfortunately for your conscience and peace of mind, they are Christian, and while you're busy disavowing them, they're busy killing people like me, either directly (hate crimes), legally (policy that disadvantages queers and makes us more vulnerable, in much of the Western world, or just straight out outlawing us, in many other places) or indirectly (the atmosphere of hatred and intolerance that fuels homophobic bullying and drives people to suicide). It is Christian groups in the US that are pushing for death penalties in Africa. It's Christian groups that threaten to stop helping the needy if gay marriage passes. I suppose you can argue that Catholicism isn't Christianity, but most of us queers are probably still going to want to stab you in the face if you honestly try to pull a No True Scotsman on the Catholic Church. Yeah, yeah, they're regressive and no one cares about them anymore-- oh wait except the fuckton of people who do. Turns out they have massive influence in South America, Africa, much of the Pacific... a lot of countries that have suffered pretty badly through the era of colonialism and in the years since, largely because of the policies put in place by Christian conquerors.
After all, if you do a bit of research it's pretty easy to find information about the prevalence of particularly transgender or third-gender people in cultures literally world-wide, as well as same-sex behaviour that may or may not be equivalent to our current ideas of being gay or lesbian or bisexual. (I hold that those concepts are fairly modern, in their current form, so you can't really make the claim that someone like Alexander of Macedon was gay - it's something that just didn't apply in that time period. It would be like calling a historical figure a beatnik, except obviously also quite different because beatniks are nothing at all like queer folk. Well, unless they're also queer.) It's also pretty easy to find evidence that most or maybe even all of these cultures were a lot more stable and healthy before they were kindly colonised and subjugated and forcibly converted to Christianity, but again, that's edging off towards a tangent, albeit a very related one.
You know, if you actually take a step back and think about it, it's incredibly fucked up that gay and transgender rights should be up for discussion at all. We are a pretty huge number of people. We are normal. We are natural. We have always existed in some form or other. There are hundreds and hundreds of species of animal where same-sex romantic or sexual behaviour is well-documented. Yet it's actually pretty damn normal for people to honestly, genuinely debate over whether or not we deserve to have the same rights as anyone else. Even in New Zealand, which is often regarded as pretty liberal, though depressingly increasingly less so at the moment, gay couples can't adopt. One partner can, by themselves, but the other would have no legal rights as a parent despite participating just as much in the day to day raising of their child. There are plenty of other issues too, that's just one that's come up recently because of the big gay marriage debate (which would grant us adoption rights).
And really that paragraph, right there, is why I hate Christianity. Because it has made me into the subject of a public debate. Because it teaches people to be disgusted by my existence. Because it encourages violence. Because me having equal rights is so abhorrent that it outweighs hundreds of problems that the millions and billions of dollars spent on political campaigns and lobbying could help to solve. And, also, because so many Christians would rather argue with me about this than actually try to change it into something that would better represent the 'tolerance'* they claim to have.
(*I don't want your 'tolerance', btw. You tolerate eating vegetables you hate for dinner. You tolerate bad behaviour out of politeness. I will never settle for tolerance.)