Paul had the ministry of preaching to the Gentiles.
Paul was not sufficient of himself to attain the knowledge of the gospel truths which he preached. His sufficiency came from God. It was the Spirit of God Who enabled him to preach the Word powerfully. (2 Corinthians 3:5-6)
Paul used great boldness of speech. He knew the Spirit of God was working in him and through him to free sinners. It is the Spirit of God who takes the veil away. It is the Spirit of God who gives liberty from the bondage of the sin Adam gave us. By the Spirit of God we hope and behold the glory of the Lord.
The whole Christian life is from faith to faith. All Christians need the mercy and grace of God from time to time.
Christians are fallible. But as Christians, we do not lose heart. We have a living hope in the Spirit of God.