VATICAN CITY — Pope Leo XIV affirmed Friday that the family is founded on the “stable union between a man and a woman,” and that the unborn and elderly enjoy dignity as God’s creatures, articulating clear Catholic teaching on marriage and abortion at the start of his pontificate.

Leo, the first American pope, also called for reviving multilateral diplomacy and promoting dialogue between religions in the search for peace, in his first meeting with the Vatican diplomatic corps. The audience was private, but the Vatican released Leo’s prepared text and that of the dean of the diplomatic corps.

The encounter is one of the protocol requirements after a conclave, allowing a new pope to greet representatives of world governments ahead of his formal installation Mass this Sunday. The Holy See is a sovereign state under international law, has diplomatic relations with over 180 countries and enjoys observer status at the United Nations.

Leo, a member of the Augustinian religious order, has emphasized peace as a priority of his pontificate, from the first words he uttered on the loggia of St. Peter’s Basilica after his May 8 election, “Peace be with you all.”

In his remarks, he said the search for peace was one of the pillars of the papacy. He insisted that peace isn’t just the absence of conflict but a “gift” that requires work, from an end to the production of weapons to choosing words carefully. “For words too, not only weapons, can wound and even kill.”

He said it was up to governments to build peaceful societies “above all by investing in the family, founded upon the stable union between a man and a woman.”

“In addition, no one is exempted from striving to ensure respect for the dignity of every person, especially the most frail and vulnerable, from the unborn to the elderly, from the sick to the unemployed, citizens and immigrants alike,” he said.

Pope Francis strongly reaffirmed core Catholic teaching opposing abortion and euthanasia, saying they were evidence of today’s “throwaway culture.” But he also made reaching out to LGBTQ Catholics a hallmark, insisting they are welcome in the church. He never changed church doctrine defining marriage as a union between man and woman and homosexual acts as “intrinsically disordered.”

As the then-head of the Augustinian order, the Rev. Robert Prevost in 2012 criticized the “homosexual lifestyle” and the role of mass media in promoting acceptance of same-sex relationships that conflicted with Catholic doctrine. A decade later, during Francis’ pontificate, he acknowledged Francis’ call for a more inclusive church, and said he didn’t want people excluded just on the basis of their lifestyle.