Pope Francis has been urged by a group of prominent conservative Christians to uphold traditional marriage even as the Catholic Church prepares to review its attitudes towards the issue.
In an open letter ahead of an upcoming synod of catholic bishops on the family, the group of 48 intellectuals and preachers urges the pontiff to defend orthodox Christian teaching on marriage.
The letter does not explicitly touch on the global trend towards legalising gay marriage or the ongoing controversy within the Church over whether divorced and remarried believers should be able to receive communion.
But it addresses the criticism the church has received in recent years over its stance on those issues.
The letter urges Francis to use the October 5-19 synod as an opportunity to "express timeless truths about marriage" and demonstrate how they "represent true love, not 'exclusion' or 'prejudice' or any of the other charges brought against marriage today".
Citing a US divorce rate of more than 40 percent, the group voices alarm over the growing trend towards unmarried cohabitation and the threat pornography supposedly represents for couples.
It urges the Church to resist or seek to roll back laws that redefine marriage -- as recent legislation on gay unions has done in many countries -- or make divorce easier, as "no fault" and quickie arrangements become more common.
The Church is also urged to commission research into the impact of pornography and to encourage priests and parishioners to promote lifelong marriage through their sermons and through mentoring work.
"Men and women need desperately to hear the truth about why they should get married in the first place," the letter states.
"And, once married, why Christ and the Church desire that they should remain faithful to each other throughout their lives on this earth."
Signatories to the letter include a former US ambassador to the Vatican, Mary Ann Glendon, now a Harvard professor, a well-known US evangelist, Rick Warren, and Marcello Pera, a former speaker of the Italian Senate.
- Cardinals clash -
The letter follows the pre-synod outbreak of sparring amongst cardinals on different sides of the divorced believers and communion debate.
German cardinal Walter Kasper, a close ally of Francis, is the leading advocate of the Church finding a way of allowing remarried divorced people to receive communion. The rite, for the faithful, signifies the embrace of Christ and his teaching through the symbolic eating of his flesh and drinking of his blood, represented by the sacraments of a wafer and wine.
US cardinal Raymond Leo Burke on Wednesday accused Kasper of talking in Francis' place. "As far as I'm aware the pope does not have laryngitis," Burke said in an ironic quip quoted by Italian daily La Stampa.
The camp of conservative cardinals also includes Australian George Pell and German Gerhard Ludwig Muller, both senior figures in the Vatican hierarchy.
The main opposition to any relaxation of the Church's stance on marriage comes from the United States, where some Catholic figures accuse Francis of not doing enough to support them in their opposition to contraception and abortion.