Today is Blasphemy Day. In honor of that, here's some blasphemy: There is no god. Jesus was just a man. Mohammed was not a prophet. A cracker cannot turn into flesh. Thunder and lightning are not caused by Thor or Zeus. Heaven and hell do not exist. Sex is a good thing. The presents under your tree weren't left there by Santa Claus.
Doubtlessly, you believe at least one of these things. Which is why I support Blasphemy Day. Because something you believe is blasphemy to someone. The price you pay for being able to express it is that others can express something that you may disagree with or find personally offensive. To oppose that is to oppose the very concept of free speech.
And so here's another piece of blasphemy: Faith is a bad thing.
In this context, by faith, I mean belief without reason. The word is sometimes used to mean something more like trust. A common arguing technique by some believers is to deliberately confuse the two separate meanings. ("You have faith that your brakes will work, which is the same as my faith in god.") Let me be clear, I am talking about belief without reason. If you have a reason for believing something, it's not faith.
Why is faith a bad thing? Because it's fundamentally irrational. You can't draw a map without first looking at the territory. Something you believe by faith might be, by pure chance, correct. But given all the different mutually exclusive things you could believe by faith, that chance isn't very good. If you're actually interested in having your beliefs be correct, faith is a very bad approach to take.
Now, evidence can be misleading. People believe things that are incorrect, but with backing evidence all the time. For example, scientists at the end of the nineteenth century believed in luminiferous aether and with good reason. Light's a wave, it has to travel through something, right? But by always evaluating new evidence, you can correct your mistakes and make your beliefs closer to the truth. With faith, there is no such recourse.
Faith is a bad thing, but what's even worse than faith is the belief that faith is a good thing. Human irrationality is a bad thing, but it's an inevitable thing. We are not rational beings by nature, and a certain amount of irrationality is to be expected. But it is not to be desired. We must strive to be as rational as possible, because that is the only way we can progress. It is the only way to correct our mistakes and fix them.
Promoting faith as a paramount good is perhaps one of the most evil things religion has ever done (well, ok, crusades, pogroms, fatwas, etc. are pretty bad too).