Religion is bullshit

Religion is bullshit!

There, I said it.
If you believe in an afterlife or an intelligent being who's actively interested in human affairs, you're not only (likely) remarkably wrong, but I simply don't think you've done enough thinking on the matter.
Religious people can respond to rational criticism in one of 3 ways: by asserting that their religion is true, by asserting that religion has utility outside of its truth (it's useful to society) or by asserting that being irreligious is associated with moral depravity and other undesirable outcomes.
This last claim is the most easily refuted by simply looking at the world. The most atheistic countries on Earth (such as Norway) rank higher than more religious ones in nearly every measure of human well-being, from literacy and employment rates to life expectancy and GDP per capita. Even among US states, the most religious tend to have higher rates of crime and lower literacy and education rates.
Correlation doesn't imply causation, but these facts make it clear that societies aren't crumbling because their citizens are becoming too rational.

Why Be Such A Bitch About It? What did religion ever do to you?

There are really only two things wrong with religion: it isn't true, and it's evil.
The fact that it isn't true doesn't offend me that much: people believe in dumb bullshit all of the time without a good reason.
Even still, it's disheartening to meet otherwise well-educated, respectable people who actually believe in 40-day worldwide floods, human resurrection, and talking snakes.

Now, people have the right to believe whatever the hell they want to believe. I'm not against that: it's a basic human right.
What I'm against is people's personal, bullshit metaphysics influencing the real world. See, I think that religiously oppressed homosexuals, victims of terrorism (including 9/11), millions in Africa dying of AIDS, millions more who will die from illnesses treatable with stem cells, and every brainwashed child deserves an apology.

H.L. Mencken said, “We must respect the other fellow's religion, but only in the sense and to the extent that we respect his theory that his wife is beautiful and his children smart.”
Religious people shouldn't get tax-exempt organisations, appallingly free reign to molest children, and disproportionate government representation.
Their ideas also shouldn't be beyond criticism. Nothing should. More on all of this some other time.
For now, let's just say that humanity is right to value truth and we're right to criticise bad ideas. If someone states that they think Elvis is still alive, they're laughed out of a room, but if that same person draws a cartoon depicting a 1400 year-old prophet, most first world countries find it acceptable that he receives a litany of death threats.
Are we really, as a society, OK with this? You wouldn't make it 10 seconds in politics (or anywhere but an asylum) saying that you believed in Thor and convened with him regularly, but if you don't say the same thing about a less-creatively named god, you are immediately precluded from standing any chance whatsoever of holding any political office in most of North America (which we all know is one of the most religious countries in the world).
Clearly, something has gotta give.

God Isn't Real

The arguments (and anger) presented above only really matter if gods don't exist. If there is indeed a supernatural being, then maybe these religious people have it right and I'm just the worlds most misguided arsehole. Wait though... which religious people?

As Bertrand Russel said, even if the sky opened up right now and a voice boomed simultaneously into every human mind saying “I am the one true deity!” followed by a bitching light-show, every theist should STILL expect to be wrong, simply on probability.
See, there are a lot of religions out there. And, as much as multicultural, tolerant society would have you believe, they're not mutually compatible.
See, either God is real or he isn't. Either Jesus was his son, or he wasn't. Either Mohammed was the true prophet or he wasn't.
There is simply no possible way for everyone to be right. Miracles and creation stories lose a lot of panache when you realise that they're ten to the dozen and are available from literally thousands of retailers.

Prove It!

Also, it isn't my duty to prove that God doesn't exist. Proving a negative is nearly impossible, and there is a world of difference between claiming that “there's a poorly-defined creator of the big bang” and claiming that “God exists, he made the Earth 6000 years ago, he wrote a book, he had a son, he doesn't like gays, he runs the afterlife, and he's coming back any day now to judge us all.”
Most of these other claims (and many many other ones that certain religious people will offer) CAN be disproved.
We know that the Earth is billions of years old through a huge battery of independently-verifiable testing methods.

We have no reason to believe in an afterlife because such a belief would force us to revise EVERYTHING we know about biology, chemistry, and physics.
We'd need to throw out the books on countless theories that have provided us with testable, repeatable, and useful models that describe the natural world to a startling degree of precision.

Think about it like this: name me any phenomenon in the whole fucking universe that has ever been fully understood. Guess what? It works without any supernatural hand-waving. And just because we don't have the answer to every question doesn't mean that god wins by default.
Right now, god is simply a receding sphere of scientific ignorance. Before people understood micro-organisms, they thought that illness was caused by spirits.
Before people understood the cosmos, they thought that the Earth was the flat centre of the universe. Right now, people don't understand the origin of the first self-replicating molecule, so they think that god did that.
See the problem? A real explanation is out there, and we're not going to get any closer by sitting back and saying “praise the lord.” God has NEVER been the answer to any rational question we've ever asked. Why do we think that the current crop of mysteries are any different?

Unfortunately, whenever you bring up science in a discussion with religious people, they say that “God works in mysterious ways” and that he can't be measured.

Let me get this straight: God exists, but he doesn't do anything that can be measured. Does he or does he not heal people? That can be measured. It seems that god's kind of an arsehole to amputees though, and only chooses to heal afflictions that can also undergo spontaneous remission without him.
He never seems to perform miracles that break the existing laws of physics or probability. If you believe in god, you need to answer this question: what's the difference between the universe we live in, and a hypothetical universe where there is no god? If there is a difference, then it must be measurable. If there isn't a difference, then why do you believe in god?

Reject Religion

Question your beliefs. To pick on Christianity (again), here is what you need to reject to think that it is bullshit.
You don't need to disprove the existence of souls. You don't need to be able to answer every corner-case question in quantum physics. You need to reject the literal truth of the Bible, a 2000 year-old text written in the pre-scientific Roman empire by non-contemporaneous authors, edited and interpolated over the centuries by countless flawed humans and filled with miracles either so unbelievable that they are humorous or so uninteresting and trite that they couldn't fill an hour on TLC.

If this is offensive, it's because I'm offended.
If you are reading this post, it is literally impossible for you to have ever even met someone with as ignorant a world-view as the founding figures of major modern religions.
If we want to build a global culture free of needless violence, oppression, molestation, misogyny, homophobia, genocide, and suffering, then we need to start thinking rationally, we need to start criticising bad ideas,and we need to close the curtains on religion forever.
As Sam Harris notes, it can be done quickly and easily. Look at how fast attitudes have changed about racism, homosexuality, and women's rights in the past 50 years.
All we need to do is start asking questions and not letting faith scam a free ride on the logic train. I think that humanity is better than this. I know that we can overcome this embarrassingly persistent mental affliction.

The universe is much more marvellous when seen for what it really is. So open your eyes.