Growth of religion

Growth of religion involves the spread of individual religions and the increase in the numbers of religious adherents around the world. In sociology, desecularization is the proliferation or growth of religion, most commonly after a period of previous secularization. Statistics commonly measure the absolute number of adherents, the percentage of the absolute growth per-year, and the growth of converts in the world.

Studies in the 21st century suggest that, in terms of percentage and worldwide spread, Islam is the fastest-growing major religion in the world. A comprehensive religious forecast for 2050 by the Pew Research Center predicts that the global Muslim population will grow at a faster rate than the Christian population – primarily due to the average younger age, and higher fertility rate of Muslims. Religious conversion has no net impact on the Muslim population growth. It is projected that birth rates – rather than conversion – will prove the main factor in the growth of any given religion. While according to other various scholars and sources Pentecostalism – a Protestant Christian movement – is the fastest growing religion in the world, this growth is primarily due to religious conversion and denomination switching among Christians.

Counting the number of converts to a religion can prove difficult. Although some national censuses ask people about their religion, they do not ask if they have converted to their presently espoused faith. Additionally, in some countries, legal and social consequences make conversion difficult. For example, individuals can receive a capital punishment if they openly leave Islam in some Muslim countries.

Statistical data on conversion to and from Islam are scarce. According to a study published in 2011 by Pew Research, what little information is available may suggest that religious conversion has no net impact on the Muslim population, as the number of people who convert to Islam is roughly similar to those who leave Islam.

Some religions proselytise vigorously (Christianity and Islam, for example), while others (such as Judaism and Sikhism) do not generally encourage conversions into their ranks. Some faiths grow exponentially at first (especially, for example, along trade routes or for reasons of social prestige), only for their zeal to wane (note the flagging case of Zoroastrianism). The growth of a religion can interact with factors such as persecution, entrenched rival religions (such as established religions), and religious market saturation.