A study by the Pew Research Center has found that Islam is the most popular state religion, but Christianity is favored by governments across the world even though it is not often named in a country's documents.
The Pew report found that more than 80 countries favor a specific religion, either as an official, government-endorsed religion or by giving a particular religion preferential treatment over other faiths.
The study, released on Oct. 3, was based on analysis of data covering 199 countries and territories around the world.
The findings revealed that Islam is the most common government-endorsed faith, with 27 countries, mostly in the Middle East-North Africa region, officially enshrining it as the state religion. Islam is favored in Sudan, Syria and Turkey although it is not listed as the official religion.
In contrast, Christianity is listed as the state religion of 13 countries across the globe, including the U.K., Denmark, Iceland, Costa Rica, Dominican Republic and Zambia. It is also favored by 28 other countries even though it is not named in official documents.
The researchers noted that the roles of state religions are largely ceremonial in some cases, but some come with tangible advantages in terms of legal or tax status, ownership of land or other property, and access to financial support from the government.
Buddhism is listed as the official religion in Bhutan and Cambodia, while it is favored in Burma, Laos, Mongolia, and Sri Lanka.
Judaism is named as the state religion of Israel, while multiple religions are favored in Eritrea, Indonesia, Lithuania, Serbia, and Togo.
According to the researchers, governments that favor multiple religions typically describe the faiths as "traditional" part of the country's historic culture.
Some groups belonging to the favored faiths are provided with legal or financial benefits, such as waiving the requirement as a religious group, providing funding or resources for religious education, or providing government subsidies.
In 10 countries, the governments place tight restrictions on all religious institutions or are actively hostile to religion in general. Pew lists Azerbaijan, China, Cuba, Kazakhstan, Kyrgyzstan, North Korea, Tajikistan, Turkmenistan, Uzbekistan and Vietnam as countries where government officials seek to control worship practices public expressions of religion and political activity by religious groups.
The majority of governments across the world, however, are generally neutral toward religion. As of 2015, more than 100 countries and territories included in the study do not have an official or preferred religion. While countries like the U.S. provide benefits and privileges to religious groups, no specific group is systematically favored over others.