The Vatican's top cleric in the heart of Muslim Arabia tends to a flock of 2 million Christians spread around six desert nations. But he has to do it quietly: Most of them must still pray in secret and are forbidden to display crosses and other symbols of their faith. From his base in the emirate of Abu Dhabi on the Persian Gulf, Archbishop Paul Hinder travels the Arabian Peninsula, even slipping in and out of Saudi Arabia - the birthplace of Islam, where restrictions on Christians are the toughest. "We are tolerated, but not popular here," Hinder said in an interview in the archbishop's living quarters inside a Christian compound in Abu Dhabi, the capital of the United Arab Emirates. He spoke wearing the traditional hooded robe of his Capuchin order. The white garb blends in just fine with the Arab robes worn by men in the region, so he wears it in public - but without a cross around his neck or the belt of three knots that also mark the order. "People here know who I am, although I never wear a cross when I go outside out of respect for local conditions," said Hinter, a Swiss citizen. Still, he says, there are signs of slow change, even in Saudi Arabia, where small groups who in the past would have been punished or deported if caught practicing the Christian services are now left in peace to pray privately. The UAE and the neighboring Gulf nations of Kuwait, Qatar, Bahrain and Oman have taken greater steps. They have allowed churches to be built on land donated by the countries' rulers, though there are no outward signs that the buildings are houses of worship. On Thursday night, Hinder led a midnight Christmas Eve Mass for several thousand the faithful at St. Joseph's Cathedral in Abu Dhabi. Reflecting the diversity of the community, more than a dozen Christmas Day services will be held for 10,000 worshippers in at least eight different languages. The cathedral is in a downtown compound that's also home to Anglican, Greek Orthodox and Egyptian Coptic churches. Crucifixes, icons, rosaries and other religious symbols are allowed within the walled compound. But the buildings' exteriors are spare and flat-roofed, avoiding any church-like architecture. Besides Saudi Arabia, Hinder also oversees the needs of Catholics in Bahrain, the United Arab Emirates, Oman, Yemen, and Qatar. The vast majority of the region's Christians are migrants from the Philippines, India and other Asian nations, many of whom work as maids, civil servants or in lower management positions at banks and businesses. Yemen is the only country under his purview that had indigenous Christians. Except for two priests, however, all of Yemen's 10,000 Christians, most of whom lived around the southern port city of Aden, were driven out during communist rule in South Yemen in the 1960s. Four old churches are slowly being restored there, though it is not clear how many indigenous Christians have returned, if any. The first Catholic church in the Gulf was opened in Bahrain's capital, Manama, in 1939. Now there are seven in the UAE, four in Oman, three in Kuwait and one in Qatar, where five churches of other Christian denominations are under construction. With no indigenous Christians, Gulf nations have long been the toughest in the Middle East in restricting Christian and other non-Muslim religious practices, though they rarely cross the line into outright persecution. In other Arab nations, Christians practice openly - though in Egypt, with the largest Christian minority, they often complain of discrimination at the hands of the Muslim majority. Hinter said he is careful not to do anything that could be construed as proselytizing or seeking conversions - a major taboo in Islam. Hinter, who has been in his post for seven years, says members of his flock are tested in areas beyond religion, particularly exploitation by their employers and fear of losing their jobs in the recession. Some are not allowed to attend a church service at all by their employers, who often strictly control the lives of their maids, gardeners, cooks, drivers and nannies. "Their struggles are enormous," Hinder said. "They are often exploited and sometimes treated as human beings of second class." The biggest congregation - about 1.4 million Christians - live and work in Saudi Arabia, which is home of Islam's holiest cities, Mecca and Medina, and is ruled under the strict version of Sunni Islam known as Wahhabism. Hard-core Wahhabis vehemently resist any practice of Christianity or other religions in what they see as the heartland of Islam. Hinder travels there several times a year, but only as a private citizen, not as an archbishop. Bibles and crucifixes - and all non-Muslim religious symbols - are illegal and are confiscated at the border. The low-key Christian services that do take place cannot be led by ordained priests, so Catholics cannot attend a Mass or confess their sins. Still, Hinter said conditions improved somewhat after Saudi King Abdullah visited the Vatican in 2007 and met with Pope Benedict XVI. Christians now can gather in private houses in small groups for prayer, led by an unordained "community leader," he said. "The climate is changing, but that does not mean there will be churches in Saudi Arabia tomorrow," he said.