When we look at the role of the apostles in the early church we see that they served six main functions.
1> Taking the Gospel to the unreached areas. Paul wrote to the Romans, “It has always been my ambition to preach the gospel where Christ was not known, so that I would not be building on someone else’s foundation.” (Romans 15:20) Although first-century apostolic ministry was not limited to unreached areas, a central apostolic passion was clearly to preach in places where Christ was not yet known.
2> Planting churches upon the foundation of Jesus Christ. Paul speaks of this in 1 Corinthians 3:10-11: “According the the grace of God which was given to me, as a wise master builder I have laid the foundation and another builds upon it. But let each one take heed how he builds on it. For no other foundation can anyone lay than that which is laid which is Jesus Christ.”
Not only were the first-century apostles engaged in church planting, but, in some cases, apostolic ministry also included helping established churches return to this scriptural foundation (see Galatians 1:6-10, 3:1-3, Revelation 2:1-5). As Judson Cornwall points out in his book ‘Introducing Jesus,’ “Despite the fact the book of Acts begins with the ascension of Jesus, there is no evidence anyone in the early church perceived Him as ‘gone’ from their midst. Jesus healed persons, raised the dead, spoke, and directed the work of His disciples in the book of Acts much as He did in the book of Luke. About the only difference was the lack of His physical presence in the book of Acts. Even when they preached, the disciples thought of Jesus as present in their preaching. In those first sermons, the apostles asked the listeners to not merely believe facts about Jesus, but to encounter through their words and actions the One who died, rose again, and lives forever.”
3> Appointing and training the initial leaders of a church. When Paul and Barnabas made their second trip to Lystra, Iconium, and Pisidian Antioch, they prayed, fasted, and ordained leaders in each church (Acts 14:21-23). Paul likewise instructed his apostolic understudy, Titus, to “set in order” the churches in Crete and appoint elders in every city (Titus 1:5 KJV).