The institution of marriage as it’s been traditionally defined is under pressure from changes in demographics and modes of human reproduction, the rise of feminism, and the broad cultural acceptance of gay people. At the invitation of the Vatican, in a couple of weeks, an unusual gathering of world religious leaders will convene in Rome to take up the issue. Pope Francis will initiate the discussion, no doubt affirming participants’ desire to uphold traditional values, but also acknowledging the diversity of beliefs represented by the colloquium. What will set this event apart from others is the way in which the pontiff, with last month’s Synod of Bishops on family life, has already launched a broad reconsideration of marriage within his own Church, legitimizing a rarely seen level of diversity of Catholic thought. A transformation is occurring in human experience, with unsettling implications for religious faith, but the ground-breaking Pope from Argentina is on it, helping his Church — and now the world — to reckon with once unthinkable challenges. Francis’s influence transcends denomination — and religion itself. He is something new.

This year, Fortune named Pope Francis number one in its list of 50 best leaders. What does the unlikely pontiff’s way of leading suggest for others on the list and those who aspire to be there? Five characteristics explain his unprecedented arrival on the world stage.

1. Francis leads by example. At the recent synod, the question was, Can the Church change basic notes of its teaching about the family? Only three weeks before the bishops convened in Rome, Francis sent them a powerful message by presiding at the joint marriage ceremony of 20 carefully selected Roman couples in St. Peter’s Basilica. A Vatican statement identified those getting married as “couples like many others. Some already live together, some already have children.” For the pope to solemnize the vows of people who would once have been derided for “living in sin” was a rupture with rigid traditionalism, and a model of what he expected from the bishops at their upcoming meeting. Marriage is a matter of “real life,” he said, “not fiction.” At the synod, the bishops showed they got the point, taking up family-related questions with unprecedented openness. The pope’s preference of mercy over moralism, so firmly on display at the marriage ceremony, has already altered the hierarchy’s slant, even if it’s too soon to say what formal changes the Church will make.
2. Francis leads by invitation. For years, the European Union had been looking the other way as tens of thousands of desperate African migrants, many fleeing wars in Libya and Tunisia, risked their lives in flimsy boats to cross the Mediterranean, aiming for the island of Lampedusa, the southern-most part of Italy. Hundreds were drowning in the attempt. In 2013, Pope Francis took his first trip outside Rome to Lampedusa. With pointed drama, he used an upended fishing vessel as an ad-hoc altar on which to say Mass, and he prayed with thousands of migrants in a soccer field. As he expected, the media broadcast every moment of his visit, and all at once Europe was forced to see what was happening at its doorstep. Drowning migrants were no longer invisible. Within a few months, the European Union established a new maritime monitoring system, accepting responsibility to rescue those endangered at sea.
3. Francis leads by collegiality. The Catholic Church is the last command society in the West, and the pope could implement the changes he wants simply by issuing orders. It is clear, however, that one of his main purposes is to transform the way authority is exercised in the overly centralized Church. Exercising his own top-down power would defeat that, because the command society itself is at issue. The main structure of Roman Catholic governance is the Vatican Curia, a stultified bureaucracy, riven with fiefdoms and competing power centers. Instead of confronting the Curia as a solitary potentate, Francis by-passed it, creating an unprecedented new structure, the so-called “Council of Eight.” It consists of eight Cardinals, one from each continent, and only one of whom is a Curia member. He commissioned them to consult widely in their own regions, so that their advice on a range of questions reflects a feel for grassroots experience of the Catholic people. Most important, the Council of Eight is helping the pope to devise a new apostolic constitution, promising a drastic overhaul of the Curia, and a far more collegial power structure — one in line with that envisioned at the second Vatican council, which defined the Church not as a top-down hierarchy but as an empowered people, the people of God.
4. Francis leads, when necessary, by executive order. One of the pope’s first unilateral acts was to do away with bonuses — counted in millions of Euros — traditionally given to Vatican insiders when a new pope is elected. He gave the money away. His abrupt decision to radically alter the papal lifestyle — eschewing the apostolic palace, limousine, gilded isolation — amounted, in the hierarchical structure of the Church, to a direct order to Cardinals and bishops everywhere to change the way they live. No more “princes” of the Church. And when it came to cleaning up the scandals of the Vatican Bank, Francis efficiently replaced four of the five Cardinal overseers, empowered outside critics, and let it be known that unless the Vatican financial institution could embrace transparency and accountability, he would shut it down. Meanwhile, a leading conservative critic of Pope Francis’s initiatives has been Cardinal Raymond Leo Burke, Prefect of the Supreme Tribunal of the Apostolic Signatura, the top judicial figure in Catholicism. Under Francis, Burke said, the Church “is a ship without a rudder.” Last month, Burke confirmed reports that Pope Francis is simply removing him, sending him off to a ceremonial post. But because the pope has made clear his preference for consultation and collegiality, such rare expressly executive moves have integrity and impact.
5. Francis leads by acknowledging mistakes. His most famous statement came in reply to a question about gay priests. “Who am I to judge?” he asked. The power of that question, of course, was in its reversal of the usual exercise of papal authority, with all the creeping potency of an office long said to be infallible in matters of faith and morals. But Francis pairs his rejection of triumphalist moralism with frank acknowledgement of his own “hundreds of errors, errors and sins.” Lifting up what he calls “the grace of shame,” he admits lessons learned from “my authoritarian and quick manner of making decisions.” The pope’s refusal to rule the Church in the traditional papal style is clearly rooted in the examined conscience of a humble man, the readiness to be self-critical.

We’re all waiting to see which changes initiated by Pope Francis will take hold, and even how fully committed he is to the profound transformation many Catholics seek. It is possible that by raising hopes both inside and outside the Church, a disappointing pontificate will further erode religious and social morale. A bureaucratic, dogmatic, and misogynist institution does not change easily. But Francis has already changed the Catholic Church, for in his kindly, honest, self-affirming person many catch a glimpse of the one around whom the Church gathered in the first place.