Here apostolic succession is understood as the passing on of the grace of ordained ministry by the lawful laying on of hands, and in a broader sense, as apostolicity: the continuity and genuine preservation of faith handed down by the Apostles, as well as the continuous succession of the bishops from the Apostles onward. The former constitutes the basis, the later is an essential characteristic of apostolic succession in that deviation from apostolic teaching destroys apostolic continuity and illicit ordination by unauthorized persons allows it to be broken.

The apostolic succession in this broader sense is essential and necessary for the life of the Church in order to continue the Lord’s work of salvation through faithful transmission of sanctifying and saving grace. As Jesus Christ was sent by the Father, so He also sent the Apostles in order to gather the people of God through them and to found and build up His Church.

In their capacity as eye-witnesses of the risen Christ and in their function at the foundation of the Church, the Apostles in fact do not and cannot have successors. They have successors, however, in the apostolic mission of gathering and building up the congregation time and again through the preaching of the Word of God and presiding over the liturgical and sacramental life, especially at the celebration of Holy Eucharist.

Even though the New Testament speaks of many charisms and ministries among the faithful, it does not leave any doubt about the uniqueness, unrepeatable and fundamental significance of the ministry and mission of the Apostles. (cf. Acts 1:21-22; 1 Cor 12:28; Eph 2:20; Rev. 21:14)

The Church has its life from Christ Who is present in it and works through the Holy Spirit. Christ is the Lord of the Church and speaks to it, loves it and is the One to Whom it listens. This relationship between Christ and the Church is not only an abstract thought but a concrete reality and experience which is transmitted through persons called by Christ. As this was the case in the age of the Apostles, so must it be in our time and at all times, for the structure of the Church in its fundamental character cannot be other than the one that Christ gave it.

The Church, which as a community cannot be without this structure, must also be in continuous temporal relationship with its origin and with the Church of previous and subsequent generations. The call of ordained ministers in apostolic succession, therefore, occurs not as something totally new without connection with the origin of the Church, but as the taking up and passing on of that which occurred in the Church from the beginning. The laying on of hands with prayer in the community of the whole Church is the only sacramental means of passing on of the grace of ordained ministry to which Scripture and tradition attest.

The necessity of maintaining apostolic succession both as the continuity of apostolic teaching and as the passing on of ordained ministry and its grace of mission by the lawful laying on of hands is the teaching of the Church Fathers in general.

The Orthodox Church of the East draws attention to the necessity of apostolic succession in the above sense from the beginning and especially now and raises it whenever the question of restoring Christian unity arises. The Old Catholic Church holds fast to this necessity as well.

From: III/7 The Necessity of Apostolic Succession, The Road to Unity – A collection of agreed statements of the joint Old Catholic – Orthodox Theological Commissions.