It was once thought that the early Christians were driven out of the Gulf, forced to convert to Islam or slaughtered.
But there is little evidence to support this theory, says Rev Andy Thompson, chaplain at St Andrew’s Anglican Church in Abu Dhabi and an expert on Christianity’s long history in the region.
Evidence suggests that Christians lived peacefully for hundreds of years, coexisting with members of other faiths before moving on voluntarily.
The ruins of a monastery at Sir Bani Yas Island, off the coast of Abu Dhabi, show no sign of wilful destruction, he says.
A letter from an Iraqi Christian priest of the time, complaining that members of his congregation had embraced Islam, led Rev Thompson to believe they converted or moved of their own accord.
Some of the Christian communities established in China may have arrived from Abu Dhabi, experts now believe.
The UAE's history as a trading centre made the area more open to different cultures, says Rev Thompson, author of Christianity in the United Arab Emirates.
It may mean that the form of tolerance practised by the UAE is “built into [Emirati] DNA”.
The monastery at Sir Bani Yas, he said, was probably established in the fourth or fifth century, surviving until the ninth century.
“It was a community of monks who at that time were related to the local community through farming,” Rev Thompson says.
“They worked with the pearl divers, so there is this long history where the monks were part of the region in all sorts of ways.
“The early church had the monopoly on the wine trade, for example, which we think was grown in the Mediterranean and then distributed through here. It was quite sophisticated.
“Certainly, from the third century we hear of bishops attending church council from Oman and we think there was a theological school in Qatar.
“The evidence seems to suggest that the church leaders simply moved on.
“When you look at the archaeological remains there are no burn marks, no signs of destruction, which suggests that the monks and the increasing Islamic community lived peacefully and coexisted side by side for at least 200 years.”
One of the last mentions of Christian communities in the Gulf is an account of pearl divers asking the monks to pray for protection against a killer shark that had been terrorising them. After the ninth century, the record goes dead.
The next Christians to try to establish a permanent base in the region, Portuguese colonists, were less collegiate when they arrived in the 16th century.
They burnt homes and mutilated or killed locals before taking Holy Communion at Khor Fakkan, north of Fujairah, to give thanks for what they saw as a victory.
But once the British established dominance and agreed to a truce with local tribes, and with Portugal’s influence waning from the 17th century, attempts to convert people were less important to them than control of the seas.
When missionaries arrived in increasing numbers at the start of the 20th century, they tried to convert the local Muslim population.
But while their efforts to provide services such as medical care won respect of the residents of the Trucial States, there was no chance of persuading them to change religion, Rev Thompson says.
“They served the people in really hostile conditions, which won the good will of the people,” he says of the missionaries.
“The consequence was that they were happy to allow the church in, and for the Christian community to flourish, recognising the mutual benefits.
“But the Emiratis have a very strong Islamic identity. The doctors in those days would hold Bible lessons, the Emiratis would sit patiently through all of it and say, ‘Give me my medicine’ at the end.
“While there was a genuine respect for the workers, there was no way they were going to change their religion. But today, those missionaries would not believe the scale of the church presence here.”
“Among those to recognise the benefits of allowing the Christians to practise their faith freely was Sheikh Zayed, long before he became the UAE’s first President.
“He was ahead of the day in terms of recognising the potential his country had. He was really an extraordinary man.
“His successors have carried that on. Sheikh Mohamed bin Zayed has got a mosque, right next door, the Mary Mother of Jesus Mosque.
“He’s making that a statement as to what defines Islam in the UAE – an Islam that embraces pluralism and welcomes the stranger.”