Religious intolerance is a refusal to tolerate anything on religious grounds or, more unusually, on anti-religious grounds. Intolerance must be distinguished from criticism, however severe. To say that a religious practice is stupid, or even evil, is not intolerance. To be intolerant, one has to actually try to prohibit the practice.
An interesting example of religious intolerance in the United States of America concerns the prayer which marks the opening of the Senate. This has usually involved only Christian clergy, but there is no law that says this must be the case, and in July 2007, the Senate opened with a prayer from Rajan Zed, a Hindu cleric. Protesters repeatedly attempted to stop the prayer by shouting such phrases as,
Lord Jesus, forgive us, Father, for allowing the prayer of the wicked, which is an abomination in your sight.
Similar protests have disrupted attempts to hold Muslim prayers in the Senate.
Some countries practice much more extreme religious intolerance. Saudi Arabia, for instance, prohibits the public expression of any faith except Islam. Even within Islam, Shia Muslims face severe discrimination, and the Grand Mufti has declared that they are not true Muslims and should not be tolerated.
Religious intolerance is partly attributable to tribalism. However, justification for it is also found in the holy books, particularly of monotheistic religions. The Bible and The Qur'an both make exclusive claims to truth which specifically forbid believers from accepting other religions. While these religions have liberal traditions, which have adopted a more ecumenical approach, fundamentalists regard other faiths as blasphemous. This means that they believe they have a divine mandate for religious intolerance.