In v14-16 Paul contrasts his old life with his new life.
v14: “so extremely zealous was I for the traditions of my fathers.”
To the Galatians who were turning to rules and traditions to make themselves more pleasing to God, Paul says he’s been there, done that, got the T-Shirt. He was advancing in Judaism beyond many of his own age, but he left all that behind when God called him by his grace. So Galatians, don’t listen to men telling you what to do. Listen to God telling you what he has done.
v15-16: “he who had set me apart before I was born, and who called me by his grace, was pleased to reveal his son to me, in order that I might preach him among the Gentiles”
Paul’s conversion from Judaism to Christianity was not a replacement of the old Jewish set of rules and traditions with a new Christian set. It was God revealing Christ to him, or if you’re using the New King James Version, “in him”.
Either way, the point is you don’t get saved by obeying the correct set of rules or believing the right doctrines, you get saved by Christ. So don’t look to your belief in the right doctrines or how well you’ve kept the rules to give you hope that God is pleased with you, look at Jesus and what he did for you, and when you preach to the Gentiles, don’t preach “you’ve been following the wrong rules and believing the wrong ideas; this is what you need to believe and these are the rules you need to obey if you’re going to get into heaven”, preach Christ and what he did for us in his life on earth and his death on the cross.
In v17-21 Paul tells the Galatians about some of the travelling he did after his conversion, and I know a couple of people were hoping for a Geography lesson, but I’m afraid you’re not going to get it from me, because I don’t think Paul’s point in referring to Arabia and Syria and Cilicia was to tell us how many miles he travelled in which direction. I think the point is God revealed his son to Paul in order that Paul might preach him to the Gentiles, and that’s exactly what he did. Obviously Paul was a special case in terms of how he received the gospel. I’m not going to suggest we should stop listening to any Christian teachers and just go out and try to evangelise the nations on our own, but as well as proving the purity of Paul’s gospel, I think the fact that he didn’t feel the need to consult the other apostles in Jerusalem before he took the gospel to the Gentiles proves the power of the straightforward gospel message. Paul didn’t need to go up to Jerusalem to gain any additional insight or learn any special evangelism techniques from the experts. He just preached Christ.