More than a thousand Catholic priests have signed a letter saying that if equal marriage is legalised it could threaten religious freedom in a way last seen during “centuries of persecution” of Catholics in Britain.

In one of the biggest joint letters of its kind, the priests raise concerns that their ability to speak out about their faith  would be “severely” limited, and said the government’s ‘quadruple lock’ guarantee for religious freedom was “meaningless”, reports the Telegraph.

The letter goes on to liken Prime Minister, David Cameron’s efforts to legalise marriage equality, to Henry VIII, who, in an attempt to secure a divorce from Katherine of Aragon, triggered centuries of bloody upheaval between church and state.

Combined with equality laws, and other legal restraints, the government’s plans would threaten the freedom of Catholics working in schools, charities and other public bodies, from speaking about their beliefs on marriage, wrote the priests.

It says the freedom to speak from the pulpit would even be threatened by the upcoming legislation.

They also said that they feared that Christians who believe in marriage in a “traditional” sense would be excluded from some jobs, in the same way that Catholics were from the Reformation until the 19th Century.

The comments were contained in a letter to the Daily Telegraph, which was signed by 1,054 priests, and 13 bishops, as well as other senior Catholic figures.

This number accounts for almost one in four Catholic priests in England and Wales.

The priests write: “After centuries of persecution, Catholics have, in recent times, been able to be members of the professions and participate fully in the life of this country.

“Legislation for same sex marriage, should it be enacted, will have many legal consequences, severely restricting the ability of Catholics to teach the truth about marriage in their schools, charitable institutions or places of worship.

“It is meaningless to argue that Catholics and others may still teach their beliefs about marriage in schools and other arenas if they are also expected to uphold the opposite view at the same time.”

Bishop of Portsmouth, the Rt Rev Philip Egan, last night described the comparison between historical bars on Catholics working in certain professions as “dramatic”, but said it was not an exaggeration.

“I am very anxious that when we are preaching in Church or teaching in our Catholic Schools or witnessing to the Christian faith of what marriage is that we are not going to be able to do it – that we could be arrested for being bigots or homophobes.”

Leading Oxford University theologian, Rev Dr Andrew Pinsent, who also signed the letter, said: “We are very sensitive to this historically because of course the reformation started in England as a matter of marriage.

“We fear that what is happening now is that a network of laws are being put in place which would violate our freedom of conscience.”

He added: “I think people in the Westminster bubble have underestimated the level of concern in the country – at a local level there is great concern about these things.”

Recently, leading Catholics in Britain, including the Archbishop of Westminster, Vincent Nichols had been seen to have stepped up their attacks on David Cameron’s plans.

But this letter was initiated by local priests, the first of its kind.

Rev Mark Swires, one of the organisers, said it had taken weeks to compile the signatures but that it showed the strength of opinion in the pews.

“This is a grass roots initiative by priests, it isn’t an initiative by the hierarchy of the church.”

As part of his Christmas Day message, Archbishop Nichols attacked the government’s plan to introduce equal marriage in England and Wales and described it as a shambles.

Legal opinions commissioned by opponents have argued that teachers could face disciplinary measures under equality laws if they refuse to promote same-sex marriage once the change has been implemented.

On the suggestion that techings in schools might change, a Department for Education spokesperson said: “The Government’s proposals for equal marriage do not change anything about teaching in schools.

“Teachers will continue to be able to express their own personal beliefs about marriage.

“Schools have a requirement to ensure they do not teach anything that would be considered inappropriate to a pupil’s age, religious or cultural background and they must ensure pupils are presented with balanced, factual information about the nature and importance of marriage for family life and bringing up children… this will not change.”

Same-sex couples in England and Wales are set to be allowed to marry, under plans announced by Culture Secretary Maria Miller in the House of Commons in December. The bill should be unveiled at the end of this month.

Mrs Miller told the House of Commons that she was putting in place a “quadruple lock” of measures to guarantee religious organisations would not have to marry gay couples against their wishes, including a ban on the Church of England, and Church in Wales performing same-sex weddings.

Speaking in favour of equal marriage, on which he has said he would like Tory MPs to have a free vote, David Cameron said he did not want gay couples to be excluded from a “great institution”.