The Holy Father closed the Week of Prayer for Christian Unity with Vespers at the Roman Basilica of St. Paul's Outside-the-walls on the Monday evening. In his homily he emphasized that everyone is called to seek "full communion between all of the disciples of Christ."

Cardinal Walter Kasper, the president of the Pontifical Council for Promoting Christian Unity, the archpriest and abbot of the basilica and a host of cardinals, bishops and representatives from other Christian Churches joined Pope Benedict XVI in the celebration of Vespers. The evening prayer service coincided with the Solemnity of the Conversion of St. Paul, whose tomb is under the altar of the basilica.

"As the theme for the Week of Prayer for Christian Unity, 'You are witnesses of these things,' has reminded us, our call is to be missionaries of the Gospel," Pope Benedict said in his homily.

He recounted the story of St. Paul's conversion and his subsequent life of devotion to preaching the Word of God, which "reached it's culmination in his martyrdom," as a model of the Christian witness.

This event and the appearance of Christ among the Eleven after his death, continued the Pope, were those to which the disciples thereafter bore witness, as have believers in Christ "in every time and place."

Christian witness, "then as now, is born of the encounter with the Risen, it's nurtured by the constant relationship with Him, encouraged by the profound love of Him. Only the person who has experienced feeling Christ present and alive... sitting at table with Him, listening to Him so that their heart burns, can be His witness!" the Pope taught.

"The communion and the unity of the disciples of Christ is... a particularly important condition for greater credibility and effectiveness in the their witness."

The Holy Father concluded his message by saying that "each of us is called to do our part to take those steps that bring us towards full communion between all disciples of Christ, without ever forgetting that this is, above all, a gift of God to pray for constantly.

"In fact,” Benedict XVI stated, “the force that promotes the unity and the mission streams out from the fertile and exciting encounter with the Risen One, as happens to Paul on the road of Damascus and for the Eleven and the other disciples gathered in Jerusalem. The Virgin Mary, Mother of the Church, says 'yes' that Her Son's wish is realized as soon as possible, 'that they may all be one... that the world may believe.'"

The ecumenical movement marks a milestone this year, celebrating a century since the missionary conference between representatives from Protestant and Anglican Churches met along with a single orthodox delegate in Edinburgh, Scotland in 1910. The goal of the gathering was work towards unity and define a shared approach to spreading the Good News.