Why is religion bad?

[CapnAwesome]

I think there are so many threads stating how religion is bad and the evidence on that is so compelling that even many of the religious have to admit to it although often with the caveat that it's 'organized' religion that is bad, or man's twisting of the religion that causes it to be bad or some such. What's seems to be lacking in the discussion often is why religion is bad. What is it specifically about large groups believing something that isn't true that makes it harmful? I have my own theories on the subject, but I am curious to hear what others have to say before I share my own opinions.