An essential characteristic of Christian community is its unity in diversity, and the freedom this gives to Christians to come alive as witnesses of Christ, Pope Francis said Wednesday.

The selection of Matthias to take Judas' place among the Twelve Apostles, as told at the beginning of the Acts of the Apostles, is the "reunification of the apostolic college," the pope said June 12.

This moment "shows how in the DNA of the Christian community there is unity and freedom from oneself, which make it possible not to fear diversity, not to attach oneself to things and gifts and to become martyrs, that is, luminous witnesses of God alive and active in history," he said.

"We too," Francis urged, "need to rediscover the beauty of witnessing to the Risen, emerging from self-referential attitudes, renouncing the withholding of the gifts of God and not yielding to mediocrity."

The pope, as part of a new series of general audience catecheses on the Acts of the Apostles, reflected on the disciples' selection of Matthias to replace Judas as one of the Twelve Apostles.

Following the Passion, death, resurrection, and ascension of Jesus into heaven, the disciples are praying in the Upper Room. The selection of a disciple to fill the space left by Judas is a sign of the importance of communion, Pope Francis said.

With the addition of Matthias, "the body of the Twelve is reconstituted," he said. "A sign that communion – it is communion – that wins over divisions, isolation, the mentality that absolutizes the private space, a sign that communion is the first testimony the Apostles offer."

"The Apostles choose to live under the lordship of the Risen One in unity among brothers, which becomes the only possible atmosphere of the authentic gift of self," he stated.

Judas, on the other hand, the pope said, had received a great grace in being part of Jesus' own ministry, but he tried to "save" his own life and ended up losing it.

"He ceased to belong to Jesus with his heart and placed himself outside of communion with Him and his [disciples]. He stopped being a disciple and placed himself above the Master," Pope Francis said.

Judas sold Christ to his enemies and with the "wages of his iniquity" bought land, where, "falling headlong, he burst open in the middle, and all his insides spilled out," as Peter says in Acts 1:18.

But if Judas chose death over life, the other 11 apostles "choose life and choose blessing, they become responsible in making it flow in turn in history, from generation to generation, from the people of Israel to the Church."

With the addition of Matthias, the Twelve Apostles, he said, "are the respected witnesses of Christ's work of salvation and do not manifest their presumed perfection to the world but, through the grace of unity, they bring out an Other who now lives in a new way among his people: And who is this? It is the Lord Jesus."