John Calvin on Acts 9:20

20. Luke declareth now how fruitful Paul’s conversion was, to wit, that he came abroad by and by, “Statim prodient in publicum,” immediately appeared in public. and did not only profess that he was a disciple of Christ, but did also set himself against “Se... objecerit,” exposed himself to. the fury and hatred of the enemies, by defending the gospel stoutly. Therefore, he who of late ran headlong against Christ with furious force, doth now not only submit himself meekly unto his will and pleasure but like a stout standard-bearer fighteth even unto the utmost danger to maintain his glory. Certain it is that he was not so quickly framed by Ananias’ industry, “Opera Ananiae formatum,” formed or trained by the agency of Ananias. but that so soon as he had learned the first principles by man’s mouth, he was extolled by God unto higher things afterward. He comprehendeth the sum of his preaching briefly, when he saith that Christ was the Son of God. In the same sense, he saith shortly after that he saw Christ. And understand thus much, that when Paul intreated out of the law and the prophets of the true office of the Messiah, he taught also that all whatsoever was promised of, and was to be hoped for, at the hands of the Messiah, was revealed and given in Christ. For the words signify thus much, when he saith that he preached that Christ is the Son of God. That was undoubtedly a principle amongst the Jews, that there should a Redeemer come from God, who should restore all things to a happy estate. Paul teacheth that Jesus of Nazareth is he, which he cannot do, unless he shake off those gross errors which he had conceived of the earthly kingdom of the Messiah. Certain it is that Paul declared how Christ was promised in the law, and to what end; but because all tended to this end, that he might prove that the son of Mary was he of whom the law and the prophets bare witness, therefore Luke is content with this one word only.