Christianity is the religion of 6.5% of the population of Oman, which equals to about 300,000 people. Ninety Christian congregations exist in the country. There is little official record of Christianity in Oman until the arrival of the Portuguese in 1504, but ruins from what is thought to have been a church were located in Suhar. Additionally, Chronicle of Arbela tells of a diocese at Bet Mazunaye, an area which included Oman. However, the authenticity of the sixth-century text is disputed amongst scholars. Almost all Christians in Oman are from other countries. Most of them are from the Philippines, India or Western countries, and they are concentrated in the country's urban areas: Muscat, Sohar, and Salalah. For many Christians living and working outside of these areas, going to church is inaccessible and therefore only happens on occasion. At least one St. Thomas Christian church is present in Oman, and more than 50 different Christian groups, fellowships, and assemblies are active in the Muscat metropolitan area. The Protestant Church of Oman, the Catholic Diocese of Oman and the al Amana Center (interdenominational Christian) are recognized by the Ministry of Endowments and Religious Affairs. There is also a Christian cemetery located in Muscat, operated by the Petroleum Development Oman. Islam is the official state religion, but Article 28 of the Omani constitution protects freedom of religious practices as long as they do not violate Islamic law. Therefore, Christians in Oman enjoy a considerable amount of religious freedom, although they are bound to strict rules. For example, Christians must practice on specific land that the government has allocated for them. It is also difficult for churches to get permits for construction and permission to host public religious gatherings is challenging to attain. Private gatherings are prohibited, although this law is not always strictly enforced. Proselytizing Muslims is forbidden. There are, however, cases in which a Muslim will adopt the Christian faith, secretly declaring their conversion. In effect, they are practicing Christians, but legally Muslims; thus, the statistics of Omani Christians does not include Muslim converts to Christianity. Instruction in Islam is compulsory in public schools, but there are Christian schools in Oman. A 2015 study estimates a mere 200 believers in Christ from a Muslim background live in the country, and not all of those are necessarily citizens. Evangelism Christian missionaries from the New Jersey-based Arabian Mission established a station in Muscat in