Religious intolerance is intolerance of another's religious beliefs, practices, or lack thereof.
Statements which are contrary to one's religious beliefs do not constitute intolerance. Religious intolerance, rather, occurs when a person or group (e.g., a society, a religious group, a non-religious group) specifically refuses to tolerate the religious convictions and practices of a religious group or individual.
The interaction between rival religious groups tends in part to be characterized by vilification of one by the other, whether or not this is communicated to the rival group. Attributing negative qualities to a rival group is a natural means of ensuring the coherence and motivation of a group. In the case of religious groups this can typically extend to labelling the activities of the other as "works of the devil".