Is criticism of and opposition to religion a form of bigotry?

Wikipedia claims that a "bigot" is "a person obstinately or intolerantly devoted to his or her own opinions and prejudices, especially one who exhibits intolerance and animosity toward members of a group," and that "bigotry may be directed towards those of a differing sex or sexual orientation, race, ethnicity, nationality, region, language, religious or spiritual belief, political alignment, age, economic status or medical disability." ( http://en.wikipedia.org/wiki/Bigotry ) I hear the charge of bigotry bandied about, often reflexively, particularly by theists when atheists criticize their faith-based beliefs as irrational. Is open criticism of and disrespect for religion a form of bigotry? Or is "bigotry" a loaded concept to be used by anyone whose belief system is critically challenged?