"Do I think religious belief is irrational and unintelligent?" I am with you Size, unintelligent may sound harsh, but intelligence is to do with problem solving, and religious belief has not done much to solve human problems in the last 30,000 years or so.
You and I both, I believe, are not saying that the believer is "Irrational and unintelligent" as a person, just that their belief is. And by the same token, it is the belief that atheists attack, not the whole person, and to attack a belief, showing it to be irrational and unintelligent, does not make one a bigot.