The table below lists religions classified by philosophy; however, religious philosophy is not always the determining factor in local practice. Please note that this table includes heterodox movements as adherents to their larger philosophical category, although this may be disputed by others within that category. For example,
Cao Đài is listed because it claims to be a separate category from Buddhism, while
Hòa Hảo is not, even though they are similar
new religious movements. The population numbers below are computed by a combination of census reports, random surveys (in countries where religion data is not collected in census, for example United States or France), and self-reported attendance numbers, but results can vary widely depending on the way questions are phrased, the definitions of religion used and the bias of the agencies or organizations conducting the survey. Informal or unorganized religions are especially difficult to count. Some organizations may wildly inflate their numbers. Since the late 19th century, the demographics of religion have changed a great deal. Some
countries with a historically large Christian population have experienced a significant decline in the numbers of professed active Christians: see
demographics of atheism. Symptoms of the decline in active participation in Christian religious life include declining recruitment for the
priesthood and
monastic life, as well as diminishing
attendance at church. On the other hand, since the 19th century, large areas of
sub-Saharan Africa have been converted to Christianity, and this area of the world has the highest population growth rate. In the realm of
Western civilization, there has been an increase in the number of people who identify themselves as
secular humanists. Despite the decline,
Christianity remains the dominant religion in the
Western world, where 70% of the population is Christian. In many countries, such as the People's Republic of China, communist governments have discouraged religion, making it difficult to count the actual number of believers. However, after the collapse of communism in numerous countries of Eastern Europe and the former
Soviet Union, religious life has been experiencing resurgence there, in the form of traditional
Eastern Christianity. While, Islam however has gained considerably in the Soviet Unions former republics in
Central Asia. Following is some available data based on the work of the
World Christian Encyclopedia:
Growth rate of adherents The annual growth in the world population over the same period is 1.41%. Studies conducted by the
Pew Research Center have found that, generally, poorer nations had a larger proportion of citizens who found religion to be very important than richer nations, with the exceptions of the United States and Kuwait. In the book
Shall the Religious Inherit the Earth?,
Eric Kaufmann argues that demographic trends point to religious fundamentalists greatly increasing as a share of the population over the next century. Other scholars have argued that this may be a form of "cultural selection" that will affect future demographics due to certain religious groups having high fertility that is unexplained by other factors such as income. ==Marriage==