Jorge Bergoglio needed just a few minutes to reorient radically the Catholic Church. In the days leading up to a conclave, cardinals deliver addresses designed to help their brothers discern where the Spirit is calling the church. Some go longer, some shorter. In his 2013 pre-conclave intervention, Bergoglio didn’t waste his time. “In Revelation,” the soon-to-be-pope explained, “Jesus says that he is at the door and knocks.” The idea, he continued, is that Jesus is knocking from outside the door. But Bergoglio inverted the image, and according to notes he later gave to Cardinal Jaime Ortega, asked his brother cardinals, and indeed the whole church, to consider “the times in which Jesus knocks from within so that we will let him come out.” When the church keeps Christ to herself and doesn’t let him out, he continued, it becomes “self-referential — and then gets sick.” To avoid this, according to Bergoglio, the church must go out of itself to the peripheries, to minister to the needy. This is evangelization. This is the mission entrusted to the church by Jesus Christ — and it was precisely in this moment that he foreshadowed his program for the Catholic Church as a “field hospital” for the wounded, a profound, indeed stunning image he would deliver in a surprise interview with Jesuit Father Antonio Spadaro soon after he became pope. By calling the church a “field hospital,” Pope Francis calls us to radically rethink ecclesial life. He is challenging all of us to give priority to the wounded. That means placing the needs of others before our own. The “field hospital church” is the antithesis of the “self-referential church.” It is a term that triggers the imagination, forcing us to rethink our identity, mission and our life together as disciples of Jesus Christ. Medics are useless if the wounded cannot reach them. Those who have the bandages go to those with the wounds. They don’t sit back in their offices waiting for the needy to come to them. The field hospital marshals all its institutional resources in order to serve those who most need help now. Of course one cannot prioritize the needy without understanding their sufferings and challenges. This entails listening. We begin with a question: “How can we help?” Then they tell us where it hurts. This requires patience, docility and openness to learning about how best to serve them in the particular circumstances and relationships that mark their lives. This is neither the place nor the time for pre-diagnoses in the form of prejudgments or predeterminations. In the language of spiritual direction, we call that discernment. Discernment is a word that reminds us to seek what is possible, what is of value, what is working in the person that will help reintegrate him or her back into society. Of course, there is a risk in going out into the field of battle, of moving out of one’s comfort zone and the security of one’s experience. Pope Francis speaks about our need to leave the safety of the sacristy for the mess of being with the needy. Pastors have to be unafraid to get mud on their shoes. They have to be willing to make mistakes that come from learning from the wounded and trying new treatments. How many cures have been discovered in the urgency of combat? Improvisation can lead to creative solutions. The medicine in this field hospital has a name. It’s called mercy. The medicine of mercy is ever adaptable to meet the present need; it is available to all and requires no prescription. Mercy isn’t mercy if it resides at the end of an obstacle course, or has to compete with power, or is reserved for the wounds of a few, or — worse — requires a certain level of health before being applied. Recall the conversation Francis had with Vatican journalist Andrea Tornielli, published as “The Name of God Is Mercy,” where the pope reminds us that “‘mercy’ derives from misericordis, which means opening one’s heart to wretchedness.” Mercy is not repulsed by the infected sore, for it is made for it. Bringing the medicine of mercy to the world is the most effective way for the disciples of Jesus to recapture the joy of the Gospel. The field hospital heals the healers as well. Something transformative happens to them as they work together to serve the needy. They gain a fresh sense of purpose, hope, and joy about life as they discover new ways of healing. So it goes with the church. When the church becomes a field hospital it can radically change the way we view our community life. Instead of being defined as a group of people that live in the same neighborhood, have a common ethnic heritage or social status, regularly go to Mass or are the registered parishioners, we understand ourselves as those who take up the work of healing by sharing in the sufferings of others. We are a community that taps into and shares our talents to find creative ways to help those most in need. We already know this about ourselves, as Jesus gave us this truth at the very start of his ministry when he announced that he was sent “to bring glad tidings to the poor ... sent ... to proclaim liberty to captives and recovery of sight to the blind, to let the oppressed go free, and to proclaim a year acceptable to the Lord” (Lk 4:18-19). That is Christ’s challenge for the church today: to be a field hospital for the needy. To bring those glad tidings, not to sit back and wait for those who need them to ask. To go out, to travel to the peripheries where the oppressed reside. To be with the wounded on the field of battle. This is what is acceptable to the Lord. It is radical. Mercy always is. And as Pope Francis continues to remind us of this truth, he takes us back to our Christian roots, helping us realize that it has been with us all along. This essay was written for “A Pope Francis Lexicon,” a new collection of essays on the words that have become important in the ministry of Pope Francis. The book is co-edited by Joshua J. McElwee and Cindy Wooden and will be published by Liturgical Press on Feb. 15.