On 11 January 2013, in one of the biggest joint letters of its type ever written, over 1,000 British Catholic priests, almost a quarter of all clergy in England and Wales, signed a letter to the London Daily Telegraph arguing that same-sex marriage would restrict the freedom of Catholics to teach the truth about marriage.
In December 2012, the Conservative Government announced plans to introduce legislation allowing for same-sex "marriage" before 2015. UK Prime Minister David Cameron said religious groups would be allowed, but not compelled, to perform marriage ceremonies for same-sex couples. The Equal Marriage Bill was due to be published at the end of January 2013.
The letter came just as opponents of "gay marriage" in Britain were launching a lobbying campaign targeting MPs in 65 of the most marginal seats.
Grass roots initiative
Among the signatories were eight bishops, four abbots and the leader of the Anglican ordinariate, Msgr Keith Newton. Fr 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." The priests who signed the letter reportedly came from a wide array of viewpoints in the Church.
The priests' letter warned MPs that the proposed legislation would signal a return to penal times in that it would erode the ability of Catholics to "participate fully in the life of this country".
It said the legislation would "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".
The letter pointed out: "The natural complementarity between a man and a woman leads to marriage, seen as a lifelong partnership. This loving union - because of their physical complementarity - is open to bringing forth and nurturing children.
"This is what marriage is. That is why marriage is only possible between a man and a woman. Marriage, and the home, children and the family life it generates, is the foundation and basic building block of our society."
The letter argued that, taken in combination with equalities laws and other legal restraints, the Government's plans would prevent Catholics and other Christians who work in schools, charities and other public bodies from speaking freely about their beliefs on the meaning of marriage. Even the freedom to speak from the pulpit could be under threat.
And Christians who believe in the traditional meaning of marriage could effectively be excluded from some jobs - just as Catholics were barred from many professions from the Reformation until the 19th century.
Legal opinions commissioned by opponents of same-sex "marriage" have argued that teachers could face disciplinary measures under equality laws if they refused to promote same-sex marriage once the change was implemented. Hospital, prison and army chaplains could also face challenges if they preached on marriage being between a man and a woman.
Until 1829 Catholics and other religious dissenters in Britain and Ireland were barred from entering many professions or, in many cases, even meeting to worship under a body of restrictions collectively known as the penal laws.
Bishop Philip Egan of Portsmouth, one of the signatories, insisted that the comparison with the penal laws was "dramatic" but not an exaggeration. "It is quite Orwellian to try to redefine marriage," he said. "This is strong language but something like this is totalitarian.
"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."
Rev Dr Andrew Pinsent, a leading Oxford University theologian, 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.
"Henry VIII could have been forgiven for his adultery but he didn't want to do that, he wanted to control marriage and redefine what was a marriage and wasn't. Because the Church would not concede that point, that launched three centuries of great upheaval in English society, and from the Catholic point of view life was very difficult.
"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."
In recent weeks the Archbishop of Westminster, Vincent Nichols, and several other leading Catholics had stepped up their attacks on David Cameron's plans, echoing concern in a series of pronouncements from Pope Benedict. But the letter was the first large scale protest initiated by local priests.
Another of the signatories, Father Timothy Finigan, wrote that "the question of teaching something as true is at the heart of the debate over the freedom of the Church to teach." He added: "Congratulations to the young and dynamic priests who organised this highly significant act of witness. This issue, and the firm and clear witness of our bishops in the matter, has united the Catholic Church in our country."