In 2002, the dominant religious belief was Buddhism. Many believers practice a mixture of Mahayana Buddhism, Taoism, and Confucianism, sometimes called Vietnam's "Triple Religion." It was under Chinese rule that these three major religions and philosophical systems entered the country. Three-fourths of the population are at least nominally Buddhist. Like many Asian peoples, the Vietnamese also practiced spirit worship, a form of religious belief that was particularly prevalent among the tribal peoples.
Christianity was first brought to Vietnam in the 17th century by Roman Catholic missionaries sponsored by the French, the Spanish, the Portuguese, or the papacy. Eventually, however, propagation of the Christian faith was forbidden by the imperial court, and Catholicism could only be practiced in secret. French priests were especially active in provoking the French decision to conquer Vietnam in the 19th century.
Under French rule, Christianity prospered, and when Vietnam restored its independence in 1954, there were more than 2 million Catholics in the country, a population that increased to between 6 and 7 million in 1998.
Two millenarian religious sects, the Cao Dai and the Hoa Hao, also became popular among peasants and townspeople in the Mekong Delta. In 1998, the Cao Dai sect claimed 1.1 million adherents, and the Hoa Hao claimed 1.3 million.
Minority religions include various denominations of Protestantism, Hinduism, and Islam.
Since reunification in 1975, religious activities have been restricted, although freedom of religion is formally guaranteed in the 1980 constitution. The government granted permission in 1983 for church organizations to carry on activities that correspond to official policies, but it has cracked down on dissident elements that resist state control. In April 1999 the government issued a new decree on religion that prescribes the rights and responsibilities of religious believers. It states for the first time that no religious organization can reclaim lands or properties taken over by the State following the end of the 1954 war against French rule and the 1975 Communist victory in the south. The decree also states that persons formerly detained or imprisoned must obtain special permission from the authorities before resuming religious activities.