The doctrine of apostolic succession—central to the Catholic Church’s identity with the Church founded by Jesus in the first century—involves there being an unbroken line of bishops from the beginning of Christian history to the present.
The chain of apostolic succession, of course, started with the apostles themselves. But apostles stopped being commissioned in the first century, and so apostolic succession continues with the bishops, the successors of the apostles.
At times there has been confusion regarding the precise relationship between bishops and apostles, as well as the historical origin of the office of bishop, so it’s useful to the apologist to further explore these subjects.
Apostolic Succession Begins
Christ conferred upon his apostles the original task of shepherding the earthly Church in his absence. As the Church grew, the apostles themselves appointed different kinds of ministers to assist them.
Among the apostles there were two groups. The first consisted of the Twelve, who witnessed the whole of Christ’s earthly ministry from his baptism to his Ascension (Acts 1:21-26). The second group of apostles, including Paul and Barnabas (Acts 14:14), was not bound by this condition. Thus Paul had seen and been commissioned as an apostle by the risen Christ (1 Cor. 9:1, Gal. 1:1), though he had not been a disciple of Jesus during his earthly ministry (Acts 9, 1 Cor. 15:8).
Christ could have continued to appear to individuals and appoint them as apostles throughout the Church age. However, he chose not to do so, and so the apostles passed from the scene.
The fact that this group has not continued is a Christian teaching, though not found in the New Testament, that is universally honored among Christians, including Protestants (except for certain radical Pentecostals). Thus it can be used as a counterexample with those advocating sola scriptura.
As the apostles died, the task of shepherding the Church fell by default upon the highest-ranking ministers appointed by them. This group is known today as the bishops, who are the successors of the apostles as the highest shepherds of the earthly Church.
Due to bishops’ role as the successors of the apostles, possession of a valid episcopacy is necessary for a church to claim apostolic succession. Apostolic succession thus involves in the bishops serving as successors to the apostles, not serving as apostles. The bishops are not simply a continuation of the office of apostle; they received the governance of the Church when that office ceased.
Differences between Offices
Though modern bishops succeed the apostles as the highest shepherds of the Church, and though they belong to unbroken lines of ordination going back to the hands of the apostles themselves, the office of bishop is not identical to the office of apostle. If it were, Christ would not have allowed the apostles to disappear from the scene but would have continued to appear to and commission new apostles for the Church. There are differences between the offices of bishop and apostle:
1) The Gift of Miracles. Each apostle was endowed with the gift of miracles to enable him to perform signs validating his ministry as an apostle (2 Cor. 12:12). These manifestations provided motives of credibility showing the divine authority of the apostles and, by extension, those they appointed as successors.
Bishops do not typically receive the gift of miracles.
2) Universal vs. particular jurisdiction. Apostles were not limited territorially in the way bishops are. The mission of an apostle was to cultivate and shepherd the Church of Christ wherever he might be, giving him a universal jurisdiction (cf. Matt. 28:19-20, Mark 16:14-15).
The New Testament shows apostles engaging in missionary and church-planting work in overlapping territories around the Roman world. When the apostles entrusted non-apostles with the task of organizing and governing churches, they placed limitations —commonly territorial ones—that gave lower ministers (bishops, priests, deacons) particular jurisdictions for ministry (cf. Acts 14:23; 20:17; Titus 1:5).
3) Personal vs. collegial infallibility. Christ promised the apostles special assistance by the Holy Spirit in remembering and understanding the teachings of Christ (John 14:26). This allowed the individual apostles to exercise the infallible teaching authority of the Church, and any apostle who chose to do so could define an issue.
Nevertheless, it was expedient to emphasize the settled character of a teaching that on some occasions definitions not be made by the authority of one, but by the joint authority of all the apostles, gathered in council (cf. Acts 15).
Except for the pope acting as the successor of Peter, bishops today do not have the ability individually to exercise the Church’s infallible teaching office. They can do so only as a body, either in their ordinary teaching or when gathered in an ecumenical council (Lumen Gentium 25, Catechism of the Catholic Church 891-892).
Historical Origin
A second issue the apologist will encounter when discussing the office of bishop concerns its historical origin with respect to the office of priest. The New Testament appears to use the terms bishop(episkopos) and priest (presbuteros) interchangeably (Acts 20:17 with 20:28, Tit. 1:5-7). It also speaks of there being more than one bishop in a given church (Phil. 1:1). From the end of the first century onward there appears to have been only one bishop (see the letters of Ignatius of Antioch, A.D. 107) or one main bishop plus assistant/auxiliary bishops, such as the chorepisopus.
There is more than one way to account for the transition from one state of affairs to the other. However, it seems most likely that the individuals referred to in the New Testament as bishops or presbyters did not possess the fullness of holy orders but were equivalent to modern priests. As the apostles began to pass from the scene, they appointed certain non-apostles-e.g., Timothy, Titus, Mark, Philip, and Apollos-to oversee multiple local congregations and to appoint (Tit. 1:5) and discipline (1 Tim. 5:19-20) individual presbyters within them.
At the time, these individuals were called evangelists (Acts 21:8, Eph. 4:11, 2 Tim 4:5). By the end of the first century the term overseer (bishop) may have gravitated to them because they oversaw the individual congregations and presbyters. The term bishop, on this hypothesis, thus supplanted the earlier term evangelist.
To understand why this happened, one should note that in the apostolic age, all of the terms now attached to Catholic ministry-episkopos (overseer, bishop), presbuteros (elder, priest), diakonos (servant, minister, deacon)-were fluid in meaning and could apply to different offices. Anyone who had an oversight role could be called a bishop, anyone who was an elder in the community could be called a presbyter, and anyone in the community who served or ministered could be called a deacon.
This was true even if the person in question had the highest office of all: that of apostle. The apostles Judas and his successor Matthias could be described as having a “bishopric” (Acts 1:20). The apostle Peter could describe himself as a “fellow elder” (1 Pet. 5:1); and the apostle Paul could describe himself as a “servant” or “minister” (diakonos, 1 Cor. 3:5, 2 Cor. 3:6, 6:4, 11:23, Eph. 3:7, Col. 1:23, 25). The terms had not acquired the technical senses they did over the course of the first century.
The evidence would seem to indicate that the functions of overseeing, serving as elders, and ministering to the Christian community were all exercised by the apostles. As the Church grew, they began to discharge these functions, beginning with the lowest (which is the typical pattern with any corporation-the founders delegate the lowest functions to others first, the highest functions last). Thus the apostles appointed first deacons (Acts 6:1-6), then elders (14:23), and lastly evangelists (cf. Acts 21:8).
As the terms for these offices began to acquire their technical meanings, the servile term servant (diakonos) naturally attached itself to the lowest of these three ranks, as the more senior term elder (presbuteros) did to the second office. The high term overseer (episkopos) at first attached itself to the office of presbyter when these men were the highest ministers in local churches. Later overseer became attached to the office of evangelist when the apostles began to appoint men with the higher authority to appoint and discipline presbyters.
The understanding is further supported by the strong tradition of the Church Fathers that the three offices date from the time of the apostles, to whom early Church writers who attribute the ordination of specific, individual bishops (e.g., Ignatius [Eusebius, Ecclesiastical History 3:36], Symeon [ibid. 3:11]). The understanding is also supported by later writers’ recognition as bishops of those known in the New Testament as evangelists (Eusebius, Ecclesiastical History 3:4).
Whichever account of the origin of the office is correct, bishop was a distinct office by the late first century, the end of the apostolic age. This is evident because at the beginning of the second century, Ignatius of Antioch wrote a series of letters (A.D. 107) to local churches as he journeyed to Rome for his execution. In these letters, he repeatedly attests that each local church he passes has the three-fold hierarchy of a bishop, several priests, and several deacons.
He is so confident of this usage that he can say that without these three offices a local body cannot be called a church (Trallians 3:1-2). These facts show that the usage was already widespread at the dawn of the second century, so it must have first been established in the late first century, at the close of the apostolic age.