Acts 9:20

And he was certain days with the disciples that were at Damascus. And straightway in the synagogues he proclaimed Jesus, that he is the Son of God. And all that heard him were amazed, and said, Is not this he that in Jerusalem made havoc of them that called on this name? and he had come hither to this intent, that he might bring them bound before the chief priests. But Saul increased the more in strength, and confounded the Jews that dwelt in Damascus, proving that this is the Christ.

This paragraph reveals the basic fundamental of Christianity, namely, that Jesus is the Christ of God. This was the first message of the converted persecutor, and his last one this being the note that dominated his preaching throughout the noble career that began here.

Regarding the length of time during which Paul thus continued to preach in Damascus, see under the following verse. Also, it is not certain whether this paragraph speaks of events before or after Paul's trip to Arabia (Galatians 1:17). Paul stated that he returned to Damascus after his sojourn in Arabia; and it is likely that his preaching of the gospel was the same on both occasions, whether before he left for Arabia or upon his return to Damascus. However, because of his confounding the Jews (Acts 9:22), and Luke's immediate mention of the plot to kill him (Acts 9:23), the above paragraph is usually associated with the latter occasion of his ministry in Damascus.