Thousands of worshippers are expected to visit churches in Abu Dhabi after registering for Christmas Mass.
There will be strict protocols in place to keep the congregations safe.
The faithful wearing masks will sing hymns and recite prayers during Christmas Eve and Christmas Day services.
More than 18,000 people booked places at 64 services at St Joseph's Church in Abu Dhabi over three days from Thursday.
Tens of thousands more will join prayers online since numbers inside the church are restricted, with people socially distanced across the pews.
In his Christmas message, Bishop Paul Hinder, the pope’s most senior representative in the Arabian Peninsula, called on parishioners to join in with enthusiasm from their homes.
“Many will not be able to join the church and receive the sacraments,” said the bishop, who will lead Christmas services at St Joseph’s.
“Some of you may not sing in common ‘Silent night, holy night’, but follow the celebration on the screen and eagerly wait for the day when you can again join the community physically.”
Before the coronavirus pandemic, about 8,000 worshippers packed into the Roman Catholic church grounds for a single Christmas service.
This year, 300 people are permitted, dispersed across three prayer areas in the grounds.
The church has been decorated with red, silver and gold streamers and a nativity tableau.
Church officials said they were able to keep the doors open as a result of "very strong support" from the government and the Department of Community Development in Abu Dhabi.
"In many parts of the world, churches are closed. We are grateful and feel privileged to have this opportunity to be able to hold services," John E John, director of communication at the Apostolic Vicariate of Southern Arabia, told The National.
“The government understands that religion plays a key role. They have understood and supported us and we have worked to stringently follow guidelines.”
Counters are set up so worshippers can validate online registrations by swiping their Emirates identity card.
Parishioners must wear masks at all times, maintain a two-metre distance and are asked to come early to prevent crowding at the entrance.
The church is disinfected after every service. Food and drinks are not permitted on the premises.
The choir is reduced to three singers who will wear masks while accompanying a musician on a keyboard or violin.
The vaccines provided in the Emirates will figure in many Christmas sermons.
In Abu Dhabi’s industrial Mussaffah area, seats were fully booked for Mass with 350 parishioners registering for each service through Thursday and Friday.
“This is not even 20 per cent of our usual congregation but we are grateful to come together for Christmas that brings us the message of hope and love,” said Fr Maxim Cardoza, a priest at St Paul’s Church.
“The pandemic has been such a stressful, difficult time and people have struggled. We hope with the vaccinations, there is new hope coming for all of us.”
In Ras Al Khaimah, Fr Kent Middleton will welcome parishioners to St Luke Anglican Church for midnight Mass on Thursday.
The church is not yet open for regular Friday worship and has services only on weekdays.
It will probably reopen Friday worship in January and allow other Christian denominations that use its building to return every month in a staggered approach.
“All things going well with fighting the pandemic, inshallah, everyone should resume worship here come April 2021,” he said.
Fr Middleton said he hoped the Christmas spirit would light up people’s lives.
“During this time when so many are in despair, living in fear and anxiety, my Christmas prayer for all places of worship, whether a church, mosque, synagogue or temple, is that they will be beacons of light, pillars of strength and signs of hope for all people around them.”
Catholic churches in Dubai are shut because it would be difficult to manage the tens of thousands who would congregate each day.
In Dubai, St Mary’s church said online services would be held on Friday morning.
St Francis of Assisi Catholic church said Mass was suspended and there would be no services for Christmas and New Year.
Mosques, temples and churches across the country were closed on March 16 to slow the spread of the coronavirus.
Several places of worship reopened with smaller capacities in early July.