1,054 Catholic priests, 13 Bishops and assorted Catholic abbots have signed a massive open letter claiming that legalizing marriage equality in England is a greater threat to religious freedom in general, and Catholicism specifically, since the Reformation, the 16th Century split that led to the rise of Protestantism.
Here's a sample of the letter, via The Daily Mail:
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.
It is germane to point out here that Martin Luther, John Calvin and the other 16th Century Reformers were protesting what they found to be a corrupt, archaic Catholic church. Their efforts were clearly successful, greatly reducing number of Catholics in England (Yes, Henry VIII played a role in the church's erosion of power by erecting the Anglican Church of England, but for far different reasons, though around the same time.)
So, now we have the modern – well, as modern as it can be – Catholic Church claiming that allowing fellow human beings to marry the people they love will somehow destroy their religion. It seems to be that the only thing destroying their religion is their consistent refusal to adapt to the times.