Acts 13:9

Luke now introduced Saul’s Greek name Paul, by which he referred to him hereafter in Acts. The reason for Luke’s change at this point seems to be that here Paul’s ministry to the Gentiles really began (cf. Acts 22:21). "Paul" means "little," perhaps an allusion to his physical stature, and obviously rhymes with his Jewish name "Saul" (lit. asked). "Paul" may have been a cognomen (nickname). Paul’s first and family Roman names appear nowhere in Scripture. [Note: Longenecker, p. 420.]

"Both names, Saul and Paul, were probably given him by his parents, in accordance with Jewish custom, which still prevails, of giving a child two names, one religious and one secular." [Note: Archibald Robertson and Alfred Plummer, A Critical and Exegetical Commentary on the First Epistle of St Paul to the Corinthians, p. 341.]

Note Luke’s reference to Paul’s being filled with the Holy Spirit. We have seen that Spirit filling marked the early believers (Acts 13:9; Acts 2:4; Acts 4:8; Acts 4:31; Acts 6:3; Acts 6:5; Acts 7:55; Acts 9:17). Paul was about to announce a divine miracle designed to frustrate Satan’s work in hindering the progress of the gospel (cf. Acts 8:9-23; Acts 16:16-18; Acts 19:13-17). A true prophet of the Lord was getting ready to pronounce a curse on a false prophet (cf. 2 Chronicles 18:9-27). This fresh filling (Gr. plestheis, an aorist participle) empowered him for the task.