CASTEL GANDOLFO, Italy, SEPT. 6, 2004 ( Only marriage between a man and a woman can guarantee the survival of a society and its culture, and hence cannot be equated with same-sex unions, says John Paul II.

The Pope expressed this conviction Saturday when he received the letters of credence of Donald Smith, the new ambassador of Canada to the Holy See.

At the same time, the Holy Father acknowledged "Canada's generous and practical contributions to the building of a world of peace, justice and prosperity."

"For generations, Canadians have recognized and celebrated the place of marriage at the heart of your society," the Pontiff noted, as he expressed concern over the rapid social changes under way in the North American country.

"Established by the Creator with its own nature and purpose, and preserved in natural moral law, the institution of marriage necessarily entails the complementarity of husbands and wives who participate in God's creative activity through the raising of children," the Pope explained.

"Spouses thereby ensure the survival of society and culture, and rightly deserve specific and categorical legal recognition by the state," the Holy Father said.

"Any attempts to change the meaning of the word 'spouse' contradict right reason: legal guarantees, analogous to those granted to marriage, cannot be applied to unions between persons of the same sex without creating a false understanding of the nature of marriage," he added.

John Paul II did express his admiration for Canada. "Indeed, solidarity with developing nations is a well-known and laudable trait of your people, evidenced, among other things, by your nation's notable involvement in peacekeeping missions and the production of low-cost medicines for poorer nations," he told the ambassador.

"In this regard, as Your Excellency observed, during 35 years of diplomatic relations the Holy See has worked together with Canada on a number of projects for the betterment of disadvantaged people and communities, including the promotion and application of the Ottawa Convention on land mines and the WTO [World Trade Organization] agreement on intellectual property and public health," he added.

"Similarly, with other countries, Canada and the Holy See have endeavored to bring stability, peace and development to the Great Lakes Region in Africa," he said.

Lastly, the Pope applauded Canada's success in the "integration of the multiple ethnic communities now found in your country," illustrating to "other nations that the respect due to every person is rooted in the common origin of all men and women, rather than in the fact of differences between peoples."

"It is this sublime and fundamental truth concerning the human person -- created male and female in the image and likeness of God -- which constitutes the immutable basis for all other anthropological truths," John Paul II concluded.

The new ambassador, Donald Smith, is a career diplomat who until now was division director of the Canadian Ministry of Foreign Affairs.