Our Lord told His disciples that He would send the Spirit, ''And He shall bear witness of Me; and ye also shall bear witness, because ye have been with Me from the beginning'' (John 15:26,27). Our Lord fulfilled His promise on the day of Pentecost, and poured forth the Holy Spirit upon His disciples (Acts 2:16,17,33), and from that moment, as they bore witness to the Saviour, the Holy Spirit bore witness at the same time in the hearts of the hearers, and multitudes were converted to the Lord.
''We are His witnesses of these things,'' said Peter, ''and so is also the Holy Ghost, whom God hath given to them that obey Him'' (5:32). Throughout the book of Acts, we see the mighty working of the ascended Saviour through this twofold witness. It was He who shed forth the Holy Spirit at Pentecost (2:33). It was He who chose the workers and selected their various fields of service. His last words to His Church before He ascended were, ''Ye shall be witnesses unto Me both in Jerusalem, and in all Judea, and in Samaria, and unto the uttermost part of the earth'' (1:8). The infant Church was slow to recognize the breadth of this commission and to lay aside its Jewish prejudices. They confined their preaching to Jerusalem till persecution was allowed to scatter them. The blood of the first martyr, Stephen, proved indeed [to be] the seed of the Church. It was one of the means used in preparing the great Apostle of the Gentiles [8:1-4].
Those that were scattered abroad went everywhere preaching the Word. Philip preached Christ in Samaria, with the result of a great ingathering. Caesarea (8:40), Phenice, Cyprus, Antioch (11:19), Damascus (9:2), heard the Word. The direct intervention of the risen Saviour is seen in the admission of the Gentiles into His Church. He used Peter to open the door of the Gospel to the Jews at Pentecost [ch. 2], and to the Gentiles in the house of Cornelius [ch. 10], and so fulfilled His promise concerning the keys (Mat 16:18,19).
The risen Saviour appeared to Saul of Tarsus [ch. 9], to make him ''a minister and a witness'' (26:16), to send him ''far hence unto the Gentiles'' (22:21); and at every step of his three great missionary journeys, He made known His will with unmistakable clearness. The record of the book of Acts mainly clusters around these two Apostles: Peter, the Apostle to the dispersed of Israel; Paul, to the Gentiles. It deals chiefly with the devoted labors of the Apostle Paul, the last called, but most honoured of the Apostles, and shows us that it is his name, and not that of Matthias [1:15-26], that we must look for among ''the twelve Apostles of the Lamb'' (Rev 21:14). The book opens with the preaching of the Gospel in Jerusalem, the great center of the Jewish nation. It closes with its preaching in Rome, the great center of the [gentile] world-power.
The book of Acts is the best guide-book to missionary enterprise. It tells us the true motive, the best plans, and the source of power. Guided by their risen Lord, the Early Church pursued a definite program in its extension, always selecting some great radiating center of population for its operation, whence the influence might spread to the surrounding district-- Jerusalem, Samaria, Antioch, Cyprus, Iconium, Lystra, Derbe, Philippi, Thessalonica, Berea, Athens, Corinth, Ephesus, Rome. Their methods were simple, straightforward, and successful. They went forth in dependence on the living God, with unquenchable zeal and undaunted courage. Their one aim was to bring men to a saving knowledge of Christ. He was their one theme, and the Word of God their efficient weapon. Christ was always and everywhere the center of their testimony, and the Holy Spirit their power for service. (Moorehead)
[For a verse by verse study of Acts, see the Book Notes on Acts.]
By birth a Hebrew, by citizenship a Roman, by culture a Greek, Paul was well fitted naturally to write it; but it was in the grace and apostleship received direct from Jesus Christ (1:5) that he trusted alone for his qualification. ''Thy faith hath saved thee, go in peace,'' may be taken as the Gospel germ of the Epistle to the Romans.
The clue to the Epistle is to be found in 1:16: ''I am not ashamed of the Gospel of Christ: for it is the power of God unto salvation to every one that believeth; to the Jew first, and also to the Greek. For therein is the righteousness of God revealed from faith to faith: as it is written, the just shall live by faith.'' He was not ashamed of the Gospel, for he had proved its power.
The Epistle naturally divides itself into three parts:
(1) Justification; (2) Sanctification; (3) Application of the foregoing to daily life.
Each of [these divisions] are associated with one of the great Apostle's irresistable ''Therefores...''
The second Epistle to the Corinthians contains more of Paul's personal history than any other of his Epistles, and reveals his courage and self-sacrificing love.