How do we know that the gospel is not man's gospel?

In Galatians 1:11-24, Paul passionately defends the divine origin of the gospel he preaches, stating that it was not taught to him by man but revealed to him by Jesus Christ. This assertion is important because it sets the foundation for understanding the nature of the gospel: it is a divine message that transcends human interpretation or alteration. Paul's conversion experience serves as a powerful testament to the transformative power of God’s direct revelation. He emphasizes that God, in His eternal decree, appointed him as a vessel to carry the message of grace and salvation to the Gentiles. This claims reinforces the assurance that the gospel is inherently tied to God’s will and purpose rather than human thought or tradition.