Schleiermacher maintained that 'to make proselytes out of unbelievers is deeply engrained in the character of religion.' But why do religions proselytize? Do all religions seek conversions? How are religions adapting their proclamations in a deeply plural world? This book provides a detailed analysis of the missionary impulse as it is manifested across a range of religious and irreligious traditions. World Religions and Their Missions systematically compares the motives and methods of the 'missions' of Atheism, the Bahá'í Faith, Buddhism, Christianity, Hinduism, Islam, and Mormonism. The text also develops innovative frameworks for interreligious encounters and comparative mission studies.