Those who hold for the importance of apostolic succession via episcopal laying on of hands appeal to the New Testament, which, they say, implies a personal apostolic succession (from Paul to Timothy and Titus, for example). They appeal as well to other documents of the early Church, especially the Epistle of Clement. In this context, Clement explicitly states that the apostles appointed bishops as successors and directed that these bishops should in turn appoint their own successors; given this, such leaders of the Church were not to be removed without cause and not in this way. Further, proponents of the necessity of the personal apostolic succession of bishops within the Church point to the universal practice of the undivided early Church (up to AD 431), before being divided into the Church of the East, Oriental Orthodoxy, the Eastern Orthodox Church and the Roman Catholic Church. Christians of the Roman Catholic, Orthodox, Old Catholic, Anglican, Moravian, and Scandinavian Lutheran traditions maintain that "a bishop cannot have regular or valid orders unless he has been consecrated in this apostolic succession." Each of these groups does not necessarily consider consecration of the other groups as valid.
However, some Protestants deny the need for this type of continuity, and the historical claims involved have been severely questioned by them; Eric G. Jay comments that the account given of the emergence of the episcopate in chapter III of the encyclical Lumen Gentium (1964) "is very sketchy, and many ambiguities in the early history of the Christian ministry are passed over".
He adds that this last has been controversial in that it has been claimed that this aspect of the doctrine is not found before the time of Augustine of Hippo, while others allege that it is implicit in the Church of the second and third centuries.
In its 1982 statement on Baptism, Eucharist and Ministry, the Faith and Order Commission of the World Council of Churches stated that "the primary manifestation of apostolic succession is to be found in the apostolic tradition of the Church as a whole.... Under the particular historical circumstances of the growing Church in the early centuries, the succession of bishops became one of the ways, together with the transmission of the Gospel and the life of the community, in which the apostolic tradition of the Church was expressed." It spoke of episcopal succession as something that churches that do not have bishops can see "as a sign, though not a guarantee, of the continuity and unity of the Church" and that all churches can see "as a sign of the apostolicity of the life of the whole church".