Government proposals for gay marriage would dilute an institution "vastly" important to a healthy society, the Church of England has warned.
Responding to a consultation on the issue in England and Wales, the Church said the legislation was "shallow".
Government plans to open marriage to gay couples by 2015 could undermine its status as the state church, it said.
The Home Office said religious bodies would not have to conduct gay marriages and that it was considering all views.
Gay rights campaigners accused the Church of "scaremongering".
The Church of England said that by opening marriage to gay couples, an institution defined for centuries to be exclusively between a man and a woman would have its meaning "hollowed out" and reduced to the level of a "content free", "consumerist", agreement.
It insisted that the age-old idea of marriage as being for procreation, and needing to be consummated, would not apply to same sex marriage.
The Home Office's consultation paper proposes:
- to allow same-sex couples to marry in a register office or other civil ceremony
- to retain civil partnerships for same-sex couples and allow couples already in a civil partnership to convert it into a marriage
- to allow people to stay married and legally change their gender
- to maintain the legal ban on same-sex couples marrying in a religious service
Source: Home Office consultation paper
The Church warned that creating "religious" and "civil" marriages with differing understandings of their purpose and character would serve to weaken and dilute the institution for everyone.
Church officials claimed that the exemptions from performing gay marriages, which the proposals suggest for religious organisations, would be unlikely to survive legal challenges in domestic and European courts.
They warned that the duty of Anglican clergy to perform marriages for any parishioner who wanted one might disappear, undermining the Church of England's role as the state church.
The Rt Rev Tim Stevens, Bishop of Leicester, said the Church had supported civil partnerships when the legislation was introduced eight years ago and continued to be supportive of the gay community.
"I think the difficulty we have here is the substitution of equality for uniformity, that is to say that there can be no distinction at all between men and women," he said.
"From a standing start within three months to arrive at a fully considered, weighed and articulated redefinition of a fundamental social institution which has been thought about in one particular way for centuries... to change all that on the basis of a consultation like this seems to be at the very least unwise and ill considered."
'Advocating legal discrimination'Ben Summerskill, chief executive of Stonewall, which campaigns for gay rights, said: "There's manifestly no evidence that the recognition of long-term same-sex relationships has any impact on the institution of marriage for heterosexuals.
"It seems odd that the Church of England should be obsessing about a few thousand gay couples once again when there are currently three million children in Britain living in single-parent households."
Human rights campaigner Peter Tatchell said the government's proposals only concerned civil marriages in registry offices and would have "no impact on faith organisations or places of worship".
He accused the Church of "scaremongering, exaggerating the effects of same-sex marriage and advocating legal discrimination".
"Senior churchmen are protesting against a law change that will not affect them," he said.
The Home Office said it had made it clear that "no religious organisation will be forced to conduct same-sex marriages as a result of our proposals".
"We welcome the Church of England's response and we will be carefully considering all points of view before publishing the outcome of the consultation later in the year," a spokesman said.
In April, prominent Church of England figures wrote an open letter to the Times newspaper saying the Church had "nothing to fear" from the prospect of gay marriage.
They said statements by church leaders give a false impression of popular feeling.
The government's consultation closes on 14 June.
