Anyone likely to be reading this probably also know that I’m a fairly committed atheist. I don’t think that humans have any way of reliably ascertaining truth other than through logical reasoning based on empirical evidence. In general, religious explicitly disclaims evidence-based approaches and instead advocates a faith-based approach. In other words, religions advocate blind deference to religious authority, with the only support offered the circular support of the bible or claims that popularity is in itself a form of evidence.
My brand of atheism, however, goes further than mere rejection of faith and of any sort of god or gods as a likely explanation for the mysteries of the universe. For I see not only that religion is simply wrong, but also that it causes a great deal of harm to our society, and to the world at large. There are of course the obvious means of harm like the ideas of jihad in the Islamic world or the inquisition. Great atrocities have been committed in the name of religion of course, but the harm I see as most dangerous is a much more subtle, insidious harm that can color every aspect of societies, like ours, which contain a large number of religious people of any persuasion.
The danger is faith itself. It has become a pervasive idea in many cultures, and indeed all religion must ultimately owe its support to this one, simple idea. When I say faith, I mean simply belief without evidence. I’m aware that some religious people have a hard time with that particular definition, but generally are unable to offer their own definition when prompted to do so, or change their definition fluidly as they move from one topic to another. But in the end, if your religion is based on empirical evidence, you don’t have religion: you have science. So regardless of whether you believe that “belief without evidence” is an adequate definition of faith, you must concede that belief without evidence is the core of religion, so for now I’ll simply call it faith, and if you have a problem with that, you can substitute “belief without evidence” wherever you see it (note that this may be a generally useful practice even outside this document).
Much more than any of the specific “beliefs” taught in mainstream religions, they must teach their adherents how to suspend their critical thinking skills in certain areas of inquiry (or simply never teach such skills in the first place). They teach compartmentalization of beliefs, so you can continue to believe certain things despite all the evidence to the contrary. They teach deference to authority, and suspend debate by calling certain things a “matter of faith”.
In the end, they allow irrational, ill-considered policy to win the day. Even if there is no specific conflict in the religion itself.
An example would be illuminating. Take this line of reasoning, and determine for yourself whether you think that this is a correct chain of inference:
All fish live in the sea.
Sharks live in the sea.
Therefore, sharks are fish.
It turns out that if you are very religious, you are much more likely than the average person to think that this line of reasoning is valid. After all, sharks are fish, but in fact the conclusion does not follow from the premise. A majority of the population is taught not only that their specify brand of mysticism is true, but also that the entirety of rational inquiry is wrong simply because it conflicts with the mythical beliefs, acquired via received wisdom from equally deluded parents or religious authorities.
And thus we are a society that is ruled not by reason, not by evidence, rationalism, or logic. We are ruled instead by irrationality, unreason, and, indeed, delusion.