By the Rev. James Martin SJ, special to CNN(CNN) -- At times last week, I was dumbstruck and even in tears as I followed the coverage of Pope Francis' visit to Brazil for World Youth Day.Few things have filled me with more hope about my church than the pope's past few days. For what Francis did in Rio de Janeiro, and continues to do, represents some very positive change.Monday’s surprising interview aboard his plane back to Rome, during which, in response to a question about gays and gay priests, he said, in part, “Who am I to judge?” likewise shows an openness that borders on revolutionary.At the same time, Francis called for greater mercy for divorced and remarried Catholics, and asked for a "deeper theology" of women in the church.This does not mean that I’m downplaying or denigrating Popes John Paul II or Benedict XVI. By no means.READ MORE: Pope Francis on gays: `Who am I to judge?'For one thing, there wouldn’t be a World Youth Day (not to mention a free Western Europe) without the efforts of John Paul.For another, even setting aside his many other contributions, were it not for the humility of Benedict, whose resignation made way for a successor, there would not be a new pope.Praise of Francis does not imply critique of his predecessors. Each pope brings his own gifts to the office.But make no mistake: Francis is doing is something new. And he has the potential to change the church, and in the process the world.Let’s look at five “moments” of his time in Rio—and on his flight back to Rome.The poorOther popes have visited the poor. In fact, John Paul II visited a favela in Rio in 1980. Other popes have spoken about the poor and economic injustice.The Catholic Church’s social justice tradition reaches back to the 19th century Pope Leo XIII, and, frankly, all the way back to Jesus.But I don’t think I’ve ever seen a pope embrace the poor—literally and figuratively—the way Pope Francis did during his visit to the Varginha favela. Perhaps he felt at home among the Latin America poor. During his time as Archbishop of Buenos Aires, he spent a great deal of time in the slums.READ MORE: 'Slum pope' visits Brazil's poorBut there was more. His moving address in the favela was, outside the Gospels, the most succinct summary of social justice I’ve ever heard.Again, all popes since Leo XIII have spoken on the theme, but few with such passion.It was a ringing declaration of the church’s absolute commitment to the poor: “To all people of good will who are working for social justice: never tire of working for a more just world, marked by greater solidarity! No one can remain insensitive to the inequalities that persist in the world!"The joyFrancis smiled nearly all the time during his stay in Rio. Does that sound insignificant? It is not.Joy is one of the surest signs of God’s presence, and it draws others to God. It is a powerful, but often overlooked, tool for evangelization.Everyone seems to feel comfortable with Pope Francis, which may explain the hugs.That’s one gentle distinction I might make between Francis and his predecessors. I greatly admired both John Paul II and Benedict, but I don’t think I would have felt so comfortable hugging them.That’s not been the reaction of most people toward the Jesuit pope, who seems to evoke physical affection from everyone from children to the elderly. Even from bishops, priests and nuns.A Jesuit friend met Pope Francis a few weeks ago in Rome, and told me that he instinctively hugged the Supreme Pontiff. “I couldn’t help myself!”In the Gospels, Jesus’ disciples “rebuked” people for bringing their children to him for an embrace. But Jesus rebukes them for being cold-hearted.In a church where clerics are sometimes seen as coldly aloof, joy is a tonic—and a recipe for change.The critiqueThe bluntness of Francis’ comments about the state of the priesthood, specifically about "clericalism," shocked me.Loosely defined, clericalism is the attitude that priests are better than everyone else. And this is not an obscure intra-church issue.Clericalism is one of the main reasons for the sexual abuse crisis: for if priests consider themselves better than everyone, then they will also believe they are inherently more trustworthy.Why, went the tragic thinking, should a bishop listen to victims if “Father” tells me nothing happened? Francis labeled clericalism a “sinful complicity.”In combating clericalism, rightfully in my mind, Francis offers the possibility of reorienting the church.The messFrancis clearly doesn’t mind stirring things up.In an unscripted remark in Rio, delivered in his native Spanish, he said, “What is it that I expect as a consequence of World Youth Day? I want a mess. We knew that in Rio there would be great disorder, but I want trouble in the dioceses!"In case anyone missed the point, he said, "I want to see the church get closer to the people. I want to get rid of clericalism, the mundane, this closing ourselves off within ourselves, in our parishes, schools or structures. Because these need to get out!"The official Vatican translation of the Spanish word he used, "lio," was “noise.” Spanish-speakers, however, told me that “mess” or “trouble making” may be closer to the mark.The Catholic Church needs some shaking up, everywhere. Many of us Catholics have gotten too used to the idea that people should simply come to us because we have all the answers.All of us need shaking up. Jesus understood this. Much of his ministry was about shaking things up--comforting the afflicted and afflicting the comfortable.The pope did some comforting even on the plane ride back to Rome as well.When asked in a free-wheeling news conference (in the middle of some turbulence) about the presence of gay priests in the church, he responded, “If someone is gay and he searches for the Lord and has good will, who am I to judge?”And more: “They shouldn’t be marginalized. ...They’re our brothers.”This is an act of mercy and compassion toward not only gay priests but gays in general, probably the first positive mention from a pope on the topic.The pope likewise called for greater mercy and compassion for divorced and remarried Catholics, who have long felt marginalized in the church, and asked for a "deeper theology" of women in the church.These comments betoken a remarkable shift in tone in the church. More importantly, they are a revelation of Jesus’ mercy to those on the margins.Francis is not afraid to make a “mess,” especially if the “mess” comes from mercy.The funThere’s a word you don’t see in many papal encyclicals: fun.But Jesus had fun. (What is traditionally considered his first miracle was at a wedding party, after all.)And the Pope looked like he was having a blast at World Youth Day. It didn’t bother him when his car took a wrong turn onto a busy Rio street. You could see him thinking: Who cares? This is fun! I get to kiss another baby!Francis flummoxed some of his Vatican advisers by adding several major events to his calendar, tuckering them out.Midway through the week, the papal spokesperson the Rev. Federico Lombardi, SJ, said “I'm happy we're halfway through, because if it were any longer I'd be destroyed.”Make no mistake: words and gestures mean something. In the Christian worldview, Jesus’ prophetic preaching and his miracles—healing the sick, raising the dead, stilling storms—did not just point to something coming, they inaugurated a new era.Of course the Pope is not Jesus—he’d be the first to tell you that, probably with a huge laugh!But with Francis, God is doing, to quote the Prophet Isaiah, “something new.”James Martin, SJ, is a Jesuit priest, editor at large at America, and author of "The Jesuit Guide to (Almost) Everything" and "Between Heaven and Mirth." The views expressed in this column belong to Martin.