Christian leaders have sent a pre-action letter to the Welsh Assembly calling for churches to be kept open during the 'firebreak' lockdown.
Churches in Wales are being forced to shutter over three Sundays during the lockdown, which started on Friday evening.
They will only be allowed to open for funeral or wedding ceremonies.
The Christian leaders argue that the restrictions on churches are unlawful and unnecessary, and that any decisions around closures should lie with church rather than secular authorities.
"The forced closure of churches by the state is an extreme interference with Article 9 rights. Such a far-reaching and large-scale intervention may only be justified by the most compelling scientific evidence of a resulting benefit to public health," they write.
The church leaders said they are open to constructive dialogue but will seek a judicial review if the forced closure of churches is not reversed.
Rev Peter Greasley is senior pastor at Christchurch, Newport, which runs a food bank for local people, while also providing facilities at a reduced cost to social services, the police and local health board.
He said that the restrictions would hamper the provision of these services.
"It is vital for a church that serves on the frontlines of a community in need to be able to meet and worship together," he said.
"For 25 years we have served the people of Newport and beyond materially, emotionally and spiritually."
He said he was particularly concerned that the ban "does not recognise how vital spiritual well-being is to a community".
"Through this letter we are urgently appealing to those in authority to reconsider the closure of churches and to recognise the crucial role churches play in the community across Wales and the rest of the UK," he said.
Pastor Kevin Berthiaume, Calvary Chapel Cardiff, said the Welsh Government should work with churches during the pandemic, not close them down.
"I do not envy the Government's position and recognise that the management of this crisis must be overwhelming," he said.
"However, rather than shut down churches, the government should have employed them.
"Throughout our history it has always been the influence and power of the church that has sustained people through the darkest of times."
Clyde Thomas, lead pastor at Victory Church, Cwmbran said: "At our church we work across the board with people from all walks of life. We pray with the hurting, minister to the broken, bind-up the wounds of the abused, feed the hungry, visit the prisoner, rehabilitate the addicted, and house the homeless.
"Church services are like the pit stops that refuel and enable a car to race. At a time of national crisis, local church communities are more important, not less."
Andrea Williams, chief executive of the Christian Legal Centre, which is supporting the group, said: "In the face of a crisis the answer is not to shut down churches that provide the safe havens in our communities across the nations of the United Kingdom.
"Churches are often the glue that holds our communities together; often places where the most vulnerable in our society and those hurting from Covid find community and hope.
"To shut the churches is to shut the places of refuge and rescue in our society.
"The Welsh government must think again, understand the role of their churches and allow them to be open."