The building of the largest Roman Catholic church in the Gulf was supposed to be a chance for the tiny island kingdom of Bahrain to showcase its traditions of religious tolerance in a conservative Muslim region where churches largely operate under heavy limitations.

Instead, the planned church — intended to be the main center for Catholics in the region — has turned into another point of tension in a country already being pulled apart by sectarian battles between its Sunni and Shiite Muslim communities.

Hardline Sunni clerics have strongly opposed the construction of the church complex, in a rare open challenge of the country's Sunni king. More than 70 clerics signed a petition last week saying it was forbidden to build churches in the Arabian Peninsula, the birthplace of Islam.

One prominent cleric, Sheik Adel Hassan al-Hamad, proclaimed in a sermon during Friday prayers last month, that there was no justification for building further churches in Bahrain, adding, "anyone who believes that a church is a true place of worship is someone who has broken in their faith in God."

In response, the government ordered him transferred out of his mosque, located in the elite district of Riffa, where many members of the royal family live and the king has several palaces. But the transfer order touched off a wave of protests by the cleric's supporters on social media sites and by Sunni-led political blocs. Finally, the government was forced last week to cancel the order.

The uproar reflects the widening influence and confidence of hardline Sunni groups, who have been a key support for the monarchy as it faces a wave of protests led by Shiites demanding greater political rights. Shiites account for about 70 percent of Bahrain's population of just over half a million people, but claim they face widespread discrimination and lack opportunities granted to the Sunni minority. The monarchy has also has relied heavily on help from ultraconservative Saudi Arabia, which last year sent troops to help crush protests.

More than 50 people have been killed and hundreds detained in nearly 19 months of unrest in the strategic island kingdom, which is home to the U.S. Navy's 5th Fleet. Bahrain's rulers have promised some reforms and urged dialogue to ease the crisis.

Instead, positions on all sides have hardened.

Many among the majority Shiites claim the Sunni monarchy is not interested in reforms that would weaken its near monopoly on power. Bahrain's most senior Shiite cleric, Sheik Isa Qassim, has actively opposed the church plans, questioning why the government should donate land for a Christian site when Shiite mosques have been destroyed as part of the crackdowns.

A Bahrain-based political analyst, Ali Fakhro, questioned the timing of the church project at a time when the nation is still locked in its own upheavals.

"What Bahrain needs is to solve it is own internal issues rather than adding more new things that could be the source of troubles," he said. "The plate is already full."

So far the outcry has brought no change in plans to build the church complex, which has been backed by King Hamad bin Isa Al Khalifa's monarchy. The complex will be the size of a large shopping center — about 9,000 square meters (97,000 square foot) — in Awali, an area near Riffa, south of the capital, Manama. It is to be a base for the Vatican to the small Catholic communities in the northern Gulf, as well as a spiritual center for other Christian denominations.

Work on the compound is still in its preliminary stages and no firm date has been given for its completion, leaving open the possibility of more complaints in the coming months.

The church project is part of last year's change by the Vatican to carve out a new apostolic district covering Kuwait, Bahrain, Qatar and Saudi Arabia. The administrative headquarters are expected to shift from Kuwait to Bahrain.

There are believed to be several million Christians in the overwhelmingly Muslim Gulf region, the vast majority of them expatriate workers who largely come from East and South Asia. Throughout the Gulf states, non-Muslim places of worship must work discreetly and cannot actively reach out for converts. In Saudi Arabia, churches are banned completely and any overt wearing of non-Muslim religious symbols is banned.

But Bahrain has a multi-religious tradition — and tolerance — that is unique in Gulf. The island nation has several Christian extended families which originally immigrated from Iraq, Iran or elsewhere in the early 20th Century and gained citizenship when Bahrain gained independence. Similarly, it has native Jewish and Hindu communities. The first Roman Catholic church in the Gulf was built in 1939 on land donated by Bahrain's emir.

The building of the church complex "is a sign of openness, important for Bahrain, and I hope it will serve as a model for other countries, too," the region's bishop, the Rev. Camillo Ballin, said in a statement.

Elsewhere in the Gulf, issues over Christian churches have flared in the past year.

In Kuwait, Islamist lawmakers have proposed bans on further construction of churches. Saudi Arabia's grand mufti, Abdel Aziz Al Sheik, reportedly urged for the destruction of all Christian churches on the Arabian peninsula, but it was quickly dismissed by nearly all Islamic leaders in the region.

"Bahrain is a country of tolerance among all religions, sects and races. This is well known about Bahrain's history," said the Rev. Hani Aziz of Bahrain's National Evangelical Church, who was among 19 non-Catholic Christian leaders who also met with Bahrain's king over the project. "The construction of a church falls in line with this image."