The Country Similarity Index attempts to quantify how similar countries are to each other relative to other countries. The index is a statistically-based way to measure this. 20% of the index is based on demographics. 12.5% of a country’s demographic score (2.5% of the overall Country Similarity Index score) is allocated for language. The following is an explanation on how they were calculated:
Religious Background
Religion Origins:
Christianity, Judaism, and Islam have common origins, therefore these languages are classified as Abrahamic religions. A group of religions that originated in the Indian subcontinent, including Hinduism, Buddhism, Jainism, and Sikhism, are known as Dharmic religions. Taoic religions include many religions that originated in East Asia, including Taoism, Confucianism, and Shintoism.
Religion:
The most widespread religion in the world is Christianity, followed by Islam. Hinduism is widespread among Indians, while Buddhism is most heavily concentrated in Southeast Asia. Israel is the only country with a majority of Jewish people. East Asian folk religions and traditional African religions are also seen alongside these major religions.
Denomination:
Although different people may be a part of the same major religion, there can be significant differences in their traditions and practices. Some religions were broken down into specific denominations as follows:
Christianity — Eastern Orthodox, Oriental Orthodox, Catholic, Protestant, Mormon
Islam — Sunni, Shia, Ibadi
Buddhism — Theravada, Mahayana, and Vajrayana
(Note that religious background does not include atheism or agnostic beliefs. For example, although a high percentage of people in Europe are not religious, only people in the country that follow a religion are included in the religious percentages)
The CIA World Factbook was the source of the information:
https://www.indexmundi.com/factbook/fields/religions
Calculation Method
The religions of two different countries are compared using the following method:
Example: Indonesia is 87% Muslim and 10% Christian, therefore it gets 0.9 Muslim points and 0.1 Christian points. Ethiopia is 67% Christian and 31% Muslim, therefore it gets 0.7 Christian points and 0.3 Muslim points. When religion in Indonesia and Ethiopia is compared, they receive credit for 0.3 points for Muslims and 0.1 for Christians, adding up to a total of 0.4 points out of 1.0 points.