A coalition composed of conservative Catholics and evangelical Protestants have issued a 5,000-word statement decrying the threat of gay marriage.

The statement, titled "The Two Shall Become One Flesh: Reclaiming Marriage," declared that same-sex marriages are a graver threat to Christianity and society than divorce and co-habitation.

It is signed by nearly 50 members of the Evangelicals and Catholics Together, founded by evangelical Protestant Charles Colson and Catholic priest Rev Fr John Neuhaus.  The statement will be published in conservative journal First Things in the March edition.

The group is united by their common alarm over the increasing acceptance of homosexual relationships and the growing support for gay rights, including the right to enter into same-sex marriages.

"(W)hat the state defines as marriage no longer embodies God's purposes in creation," the Herald quoted the statement as saying. 

"An easy acceptance of divorce damages marriage; widespread cohabitation devalues marriage. But so-called same-sex marriage is a graver threat, because what is now given the name of marriage in law is a parody of marriage."

The group recognises the existence of "hormonal and chromosomal irregularities" and sexual attractions that are different in nature. However, they argue that by legitimising same sex marriages, society will be forced to change their understanding of marriage.

"(Christians) are today urged to embrace an abstract conception of human nature that ignores the reality of our bodies," the group claimed. "Human beings are no longer to be understood as either male or female."

The statement also spoke of the increasing tolerance of gay marriage and rights within Christian communities. A "faithful" Christian, the coalition claimed, will not stand idly by and give in to the realities that his faith does not allow him to accept.

First Things editor Russell Reno said that the statement was a "rallying cry" to Christians against the threat of gay marriage.