LONDON -- The spiritual leader of the Catholic Church in England and Wales has praised traditional marriage as a "public good."
Archbishop Vincent Nichols of Westminster said it was "vitally important" for the "whole of society" to support marriage at a time when more British couples than ever were choosing to live together outside of marriage and to have children out of wedlock.
He said the British had acknowledged the importance of marriage by rejoicing over the April 29 marriage of Prince William and Catherine Middleton in London's Westminster Abbey.
The "mighty public cheer" that rang out after the couple exchanged vows showed an "instinctive and profound public understanding of the nature and consequences of marriage itself," said Archbishop Nichols, who was a guest at the royal wedding.
"Marriage, as a permanent, exclusive commitment between this man and this woman was welcomed, applauded," the archbishop said in a homily at a Mass for married couples in Westminster Cathedral.
"There was rejoicing in what the newlyweds had just done," he said. "Marriage, then, is a public good.
"Marriage is not simply something done in church by a few. Marriage is not a private arrangement," he said.
"Rather marriage expresses our deepest longings and expectations for ourselves, for our children and for our society," he continued.
"Marriage is of our nature. It is not created by the church, but blessed by her. Christian marriage is a sacrament," he added. "In celebrating marriage, in defending marriage, the church seeks to promote that which is good for us human beings, for our human nature and for our society."
The archbishop's words were directed primarily at a personally invited congregation of 543 married couples from his diocese who had a combined total of 18,048 years of marriage.
They gathered June 11 to celebrate the milestone 10th, 25th, 30th, 40th, 50th or 60th or more anniversaries, to renew their vows and to receive a solemn blessing.
But by releasing a transcript to the media June 10 it was clear that Archbishop Nichols intended his message to be heard by a national and not exclusively Catholic audience.
His comments came just months after official figures revealed that the marriage rate in the United Kingdom was at its lowest since 1895, with just 21.3 men marrying per 1,000 unmarried adult men and 19.9 women marrying per 1,000 unmarried women.
About 57 percent of children in the United Kingdom are now born to parents who are not married, said figures revealed in February from the Office for National Statistics.
In his homily Archbishop Nichols explained that marriage was nevertheless the key to a successful family life and the happiness and security of children because it was the most successful framework "for the relationship of love of a man and a woman to become faithful, fruitful and permanent."
He said that in contrast cohabiting relationships were inherently unstable because they were effectively negotiable.
Such arrangements were largely dependent on the fulfilment of high expectations for their success and not rooted in the mutual "acceptance of the other for who they are," he said.
"When relationships are provisional, with an understanding that each can walk away, there is a sense in which each of the partners is always on probation," Archbishop Nichols said. "They are never fully accepted."