Why is the gospel Paul preached not after man?
Paul's gospel was not after man because he neither received it from man nor was taught it by men. After his conversion he did not go up to Jerusalem to learn from those who had been with Jesus three years. Instead, he received it by the revelation of Jesus Christ.
Les teaches that in Galatians 1:11 Paul certifies the gospel he preached is not after man. Paul says he neither received it of man nor was taught it. Les explains this means Paul did not go back to Jerusalem after his conversion and ask the men who had been with Jesus three years to teach him everything they knew. Instead, Paul received his knowledge by the revelation of Jesus Christ. Les highlights the difference between revelation and instruction. As a contrast, Apollos was eloquent, famous, and seminary-taught, yet Aquila and Priscilla expounded to him the way of God more perfectly because they had been with Paul. Apollos then helped those who had believed through grace. The point is that Paul's gospel came by revelation, not human instruction.
But I certify you, brethren, that the gospel which was preached of me is not after man.