The rivalry for religious converts and influence increases the lack of religious unity and the level of religious intolerance. This may cause conflict between Church and state. One religion may lose strength to another because it supported the losing political faction in a power struggle.
Missionary activity has traditionally been the cause of noticeable rivalries. In the 18th and 19th centuries the Christian missions fought against Hinduism in India, and in the 20th century Hindu missions fight against Christianity. Beginning with more traditional Hindu missions, this century has seen the emergence of a more entrepreneurial and extravagant style in the Transcendental Meditation, Hare Krishna and Divine Light organizations, with their hundreds of thousands of followers. Friction between the devotees of these cults and the Christian community has been high.
This rivalry is not only among world religions, but among denominations, sects and cults and between all these and non-religious ideologies.