More than "theoretical discussions," what unites Christians is encounter, and a willingness to "challenge one another," said Pope Francis as he marked the conclusion of the Week of Prayer for Christian Unity.

"Christian unity will not be the fruit of subtle theoretical discussions in which each party tries to convince the other of the soundness of their opinions," the Pope said during vespers at Saint Paul Outside the Walls Basilica on Jan. 25.

"To plumb the depths of the mystery of God, we need one another, we need to encounter one another and to challenge one another under the guidance of the Holy Spirit, who harmonizes diversities and overcomes conflicts," he said.

The Week of Prayer for Christian Unity is traditionally celebrated from Jan. 18-25, between the feasts of Saint Peter and Saint Paul.

Those present at this year's Vespers included Ecumenical patriarch representative Metropolitan Gennadios, Archbishop of Canterbury representative David Moxon, and various other representatives of churches and ecclesial communities.

Pope Francis' address was largely focused on Saint John's Gospel account of Jesus' encounter with the Samaritan woman at the well. "He has no problem dealing with Samaritans, who were considered by the Jews to be heretics, schismatics, separated," the Pope said.

"His attitude tells us that encounter with those who are different from ourselves can make us grow."

In the Gospel account, Jesus asks the woman for a drink, but the Pope observes that His is more than a physical thirst: "it is also a thirst for encounter, a desire to enter into dialogue with that woman and to invite her to make a journey of interior conversion."

The Holy Father also noted Jesus' patience and respect for the woman before revealing himself. "His example encourages us to seek a serene encounter with others.  To understand one another, and to grow in charity and truth, we need to pause, to accept and listen to one another."  

"In this way, we already begin to experience unity," he said.

When the woman asks Jesus "where God is truly worshiped," the Holy Father said, Christ "goes to the heart of the matter, breaking down every wall of division.  He speaks instead of the meaning of true worship."

"So many past controversies between Christians can be overcome when we put aside all polemical or apologetic approaches, and seek instead to grasp more fully what unites us, namely, our call to share in the mystery of the Father's love revealed to us by the Son through the Holy Spirit."  

The Holy Father went on to say the "human existence is marked by boundless aspirations: we seek truth, we thirst for love, justice and freedom."

"These desires can only be partially satisfied, for from the depths of our being we are prompted to seek 'something more,' something capable of fully quenching our thirst.  The response to these aspirations is given by God in Jesus Christ, in his paschal mystery."  

The Samaritan woman's encounter with Jesus made her a missionary, the Pope continued. "Her encounter with Jesus restored meaning and joy to her life, and she felt the desire to share this with others."

Pope Francis said that "we cannot evade" the request from the many men and women who ask Christians for "something to drink."

"All the Churches and Ecclesial Communities discover a privileged setting for closer cooperation," he said. "For this to be effective, we need to stop being self-enclosed, exclusive, and bent on imposing a uniformity based on merely human calculations (cf. Evangelii Gaudium, 131).  Our shared commitment to proclaiming the Gospel enables us to overcome proselytism and competition in all their forms."

Pope Francis went on to stress that religious life "is called to offer in our time a witness to that communion in Christ which transcends all differences and finds expression in concrete gestures of acceptance and dialogue."