Pope Francis and President Donald Trump will meet May 24 in the Vatican. And while Holy See watchers debate the possible topics and tone of their private conversation, it was the Holy Father who offered a clue on his own plans for engaging the new U.S. president, who has already crossed swords with the Church leader on immigration and climate change.

“Always, there are doors that are not closed. Look for the doors that are at least a little bit open, enter and talk about common things, and go on — step by step,” said Pope Francis in response to a reporter’s question during a May 13 news conference on his return flight from Fatima.

If Francis adheres to his plan to find a tiny opening in the shared concerns of two unorthodox heads of state, Catholics may expect the Pope and president to tackle a number of looming crises, from the threat posed by North Korea’s nuclear-weapons program and the plight of persecuted Christians in the Middle East to the stalled Israel-Palestinian Authority peace talks and Venezuela’s precipitous downward spiral.

The U.S. and key Asian allies are openly debating military action against North Korea as it continues to conduct test flights of intercontinental ballistic missiles that could strike its neighbors, and, soon, perhaps California. But the Pope has called for a more intensive campaign of diplomacy and urged the United Nations to take a stronger position.

Trump and Francis may have a more fruitful discussion as they address problems faced by Christians in the Middle East and beyond. The Holy Father has repeatedly called on “political leaders to employ every means to ensure that individuals and communities, including Christians, remain in their homelands and enjoy the fundamental right to live in peace and security.” Back in the U.S., Trump is facing pressure from social conservatives to improve security and aid for Christians in Syria, Iraq and Egypt, and to provide a streamlined resettlement process for those forced to flee their ancestral homelands.

Meanwhile, the Pope and president will weigh fresh efforts to resume peace talks between Israel and the Palestinian Authority. Francis has endorsed this move, and Trump has pledged to facilitate another round of negotiations.

However, when the conversation shifts to Venezuela, where unchecked inflation, food shortages and crime sparked violent protests and a crackdown by the embattled socialist government, joint action seems unlikely. Francis has called for “peace, reconciliation and democracy” in Venezuela, but there is no robust regional effort to resolve the crisis, and Trump has said little publicly about it.

Yet it would be a mistake to reduce the Francis-Trump summit to an exchange of foreign-policy goals. Both men will also have a chance to share their thoughts about fractured Western democracies that grapple with the competing demands of globalization and nationalism.

“You are called to defend and preserve the dignity of your fellow citizens in the tireless and demanding pursuit of the common good, for this is the chief aim of all politics,” Pope Francis said during his address before the joint session of the U.S. Congress two years ago. “A political society endures when it seeks, as a vocation, to satisfy common needs by stimulating the growth of all its members, especially those in situations of greater vulnerability or risk.”

Francis is expected to return to this message with Trump, presenting an integrated vision of the common good that embraces life, marriage and solidarity with immigrants and the poor as complementary social and moral values.

Trump has adopted an unapologetically pro-life agenda, including his recent expansion of the Mexico City Policy. These measures are primarily concerned with abortion and religious freedom. But the president has yet to make a connection with policies that uphold marriage as a union of one man and one woman as a pro-life value.

Catholic and natural-law principles affirm the truth that marriage is the sanctuary of life, and any attempt to challenge that foundational social unit will pose a direct threat to unborn human life. Thus, Trump’s strong stand against legal abortion could be an opening for Francis to forge a broader vision of practices that affirm and secure human dignity and the sanctity of life.

Francis could also build on Trump’s stated respect for religious freedom and the ultimate, transcendent authority of the Creator. “[W]e don’t worship government — we worship God,” said Trump during his commencement address at Liberty University this month.

As political divisions weaken the republic, God remains the wellspring of unity. But Francis can remind Trump that it is not enough to invoke the Creator’s name; a political leader must first abide by God’s laws if he seeks to protect and defend a nation.

Likewise, Trump may reciprocate with a bold request that the Pope adopt a more generous view of U.S.-style capitalism, along with a more skeptical approach to socialist policies that fueled the destabilization of Venezuela’s once-thriving economy. At the same time, a president who arrived in office as a political outsider bent on improving job prospects for the forgotten working class may garner sympathy from the Church’s first Latin American-born pope, who has applauded the early initiatives of President Juan Peron (1946-1955, 1973- 1974), the charismatic Argentinian populist who challenged an economic and political system controlled by elites.

“At one level, President Trump and Pope Francis could not be more different,” observed Bradley Lewis, a political philosopher at The Catholic University of America. “The Holy Father is a famously austere man, an ascetic. Donald Trump has spent his life amassing a vast fortune and boasting about it. However, they have something in common: Each has set himself against a certain aspect of globalization.”

In his 2015 encyclical, Laudato Si (Care for Our Common Home), the Pope attacked trade deals that despoiled the land and left small farmers without a livelihood, while Trump has blamed NAFTA (North American Free Trade Agreement) for sending jobs overseas.

Both unique and unpredictable personalities, the Pope and president meet at a time of global crisis. They could be great, but unlikely, partners, and their first meeting will be worth watching closely. Pray for them both.