According to the National Census 2010, among Mongolians aged 15 and above, 53% were Buddhists, and 39% were Atheists:
Various forms of Tengriism and shamanism have been widely practiced throughout the history of what is now modern day Mongolia, as such beliefs were common among nomadic people in Asian history. Such beliefs gradually gave way to Tibetan Buddhism, but shamanism has left a mark on Mongolian religious culture, and it continues to be practiced. The Kazakhs of western Mongolia traditionally practice Islam.
Throughout much of the 20th century, the communist government ensured that the religious practices of the Mongolian people were largely repressed. It targeted the clergy of the Mongolian Tibetan Buddhist Church, which had been tightly intertwined with the previous feudal government structures (e.g. from 1911 on, the head of the Church had also been the khan of the country). In the late 1930s, the regime, then led by Khorloogiin Choibalsan, closed almost all of Mongolia's over 700 Buddhist monasteries and killed at least 18.000 lamas. The number of Buddhist monks dropped from 100,000 in 1924 to 110 in 1990.
The fall of communism in 1991 restored the legality of public religious practice, and Tibetan Buddhism, which had been the predominant religion in the region before the rise of communism, again rose to become the most widely practiced religion in Mongolia. The end of religious repression in the 1990s also allowed for other religions, such as Baha'i Faith and Christianity, to spread in the country. According to the Christian missionary group Barnabas Fund, the number of Christians grew from just four in 1989 to around 40,000 as of 2008
