"Am I now trying to win the approval of men, or of God? Or am I trying to please men? If I were still trying to please men, I would not be a servant of Christ." NIV translation
Paul is making the point that he works for God and not a man. If he was trying to please men, then he would not be able to share the truth with them because they wouldn't want to hear it. We have to ask ourselves who we are trying to please.
"I want you to know, brothers, that the gospel I preached is not something that man made up." NIV translation
Paul begins to explain the origin of the gospel that was given to him to preach by saying that it is not something that man came up with.
Men, will always make rules and want to do something to be saved but the true gospel is that we are saved only by God's grace.
"I did not receive it from any man, nor was I taught it; rather, I received it by revelation from Jesus Christ." NIV translation
Paul continues to explain that it is not even from man but by God. He did not go to some Bible college or other program to learn the gospel. Jesus showed up and he was changed and immediately qualified for the work that God had prepared for him. Today, more than ever, Christians are searching for some new program, title or something else to qualify them to serve God but the simple fact is that it still comes from God.
"For you have heard of my previous way of life in Judaism, how intensely I persecuted the church of God and tried to destroy it. I was advancing in Judaism beyond many Jews of my own age and was extremely zealous for the traditions of my fathers." NIV translation
Paul reminds the Galatian churches of his testimony and of how he actively opposed the gospel of Jesus Christ. He reminds them that he was following the traditions of his forefathers and defending them instead of following Jesus Christ.