Paul Kneels in Prayer in the Arabian Desertby emmanuel_higgins

Galatians 1:12

For I neither received it of man, neither was I taught it, but by the revelation of Jesus Christ.

Paul testified to the church in Galatia after his conversion that the gospel he preached did not originate with people and was neither handed to him nor taught to him by people, but came to him through Jesus Christ revealing it to him by direct instruction from God Himself rather than by human teaching or authority. That divine revealing covered both his gospel and his apostleship, which he received directly from God and Jesus Christ and not from men. He set this revelation against his former conduct in the Jews' religion, when he violently persecuted the church of God to destroy it and advanced beyond many of his own age through extreme zeal for the traditions of his fathers. His testimony is tied to the conversion told in Acts, after which he came to understand the evil work he had done once he himself had to suffer from the same human hostility that hated Christ.

After Christ appeared to him, when his life was in peril he was commissioned by God to leave Damascus for Arabia, where he spent time in communion with God without communicating with the apostles. Only after three years did he visit Jerusalem briefly, so he had no opportunity there to receive his gospel instruction from people. In comparative solitude in Arabia he was alone with God for communion, contemplation, searching of heart, deepened repentance, and preparation by prayer and study for the great and important work among the Gentiles laid upon him. There he sought God earnestly with all his heart and would not rest until he knew for certainty that his repentance was accepted, his great sin pardoned, and he had assurance that Jesus would be with him in his coming ministry. Jesus communed with him in close connection with heaven, established him in faith, and bestowed wisdom and grace upon him.

That special revelation by heavenly vision gave him knowledge of God's Word and enabled him to understand the great truths of the gospel, grasping it as taught in the Old Testament and embodied in Christ's life. God taught him directly that Gentile Christians should not be burdened with unnecessary Jewish rites and ceremonies such as circumcision, and this teaching brought the churches freedom from those rites. Its divine origin stands against teachings that distort the gospel by adding requirements such as circumcision for salvation. The revelation gave him assurance to affirm Christ as the Son of God and to preach Him as the resurrection and the life for all who believe. His preaching of righteousness by faith in Jesus was accompanied by the Holy Spirit's convincing power. He ever carried about in his body the marks of Christ's glory in his eyes blinded by the heavenly light and desired constantly to bear the assurance of Christ's sustaining grace.

Because its source was divine he proclaimed it with conviction and would not alter it to please people. This direct instruction gave him settled conviction and certainty to warn the Galatians. Receiving truth by revelation did not mean the Lord directly revealed to him every new situation in the churches: in the case of the divisions at Corinth, people reported the problem and he judged its significance in light of revelations he had received earlier, yet his reproof was nevertheless inspired by the Spirit of God.