Religious intolerance is intolerance of another's religious beliefs or practices or lack thereof.
Mere statements which are contrary to one's beliefs do not constitute intolerance. Religious intolerance, rather, occurs when a group (e.g., a society, a religious group, a non-religious group) specifically refuses to tolerate one's practices, persons or beliefs on religious grounds.
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".