Luke's history, written mostly from acquired tradition and only briefly from first hand experience with the Apostle Paul, has come down to us as the Acts of the Apostles. It is not a complete history of the early Church, but rather an outline of crucial events and turning points in the early Christian community. This is theology, history, and eternal truth woven by a master into a beautiful tapestry.
As we begin reading Acts, full of anticipation to see what happened after Christ ascended into the clouds of heaven, we find that this is not Luke's first document. Luke had written an earlier history, again told like a master weaver full of eternal truths and a deep understanding of the life and gospel of our Lord Jesus Christ. This of course is the Gospel of St. Luke written about AD 62, just before Acts. The recipient of both, Theophilus, was probably a Roman dignitary interested in the full story of this new "religion".
Luke alone provides the account of Jesus' ascension into heaven (Lk 24:51; Acts 1:2, 9-11). He also gives us the outline not only for the Acts of the Apostles but the expansion of the whole Church from the first century until today.
One hundred and twenty disciples were huddled in Jerusalem, waiting for the power of God to descend or for armed soldiers to break down the doors (Acts 1:12ff.). The Pentecost fire fell — tongues of fire leaped from each one's head, and the gift of tongues was given. The first full-fledged gospel sermon was preached with power by St. Peter concluding with the words "Repent, and each of you be baptized in the name of Jesus Christ for the forgiveness of your sins; and you will receive the gift of the Holy Spirit" (Acts 2:38).
Only Jews believed on that first Christian Pentecost. For about the first decade of the Church, no Gentiles were included. What an amazing fact — the first years of the Church were exclusively Jewish! The great persecutor Saul is converted and joins the others in spreading the good news of Christ. Peter, Paul, and the other apostles fanned out to preach and establish the Church. In Acts 13 the exciting expansion of the Church begins beyond the lands of Israel.
The book of Acts can be divided into two broad sections: the ministry of Peter (Acts 1-12) and the ministry of Paul (Acts 13-28) with a very important reappearance of Peter and other apostles in Acts 15. This marvelous chapter is the pinnacle of the whole historical account and should be held precious by all Gentile Christians, for here it was that Peter stood and again exercised the authority of the keys over the Church to proclaim that the Gentiles could be included in the full life of Christ and the Church without first being circumcised and obeying the Mosaic laws and ceremonies. This first general council of the Church, presided over by Peter, the Apostles, and the elders, resulted in an authoritative decree of the Church, which was binding upon all believers. Precedent was set for future Ecumenical Councils.
Luke is the only Gentile writer in the whole Bible, yet he demonstrates a penetrating understanding of the Old Testament and the covenants of God. The first Pentecost took place at Mount Sinai fifty days after the Passover in Egypt. The lambs' blood had been shed and the people were freed from bondage. Fifty days later (we get the word Pentecost, from "fifty"), God came down in fire upon the mountain of stone with the Law. With the brilliance and perception of a prophet, Luke shows us a direct parallel between the Old Covenant and the New — the new Passover and Pentecost.
The Acts of the Apostles is the beginning of the Church, but it doesn't end there. The Holy Spirit is still at work in and through his Church and the Apostolic Succession. Who would presume to say that the soul of the Church, the Holy Spirit, and His work stopped at the end of Acts? Has the story of the Holy Spirit in the Church ended? Of course not. Luke is letting us know the Great Commission's first chapter had been written, but the lives of the saints, bishops, martyrs, evangelists, laymen, in short the whole Church, is on an epic journey and the story will not end until Christ returns in the clouds just as He left — as the story began. Then we will have the whole story from beginning to end.