Paul's moral authority to proclaim the gospel and to say the hard things he said came from his willingness to risk his life for the gospel after he was converted. In 2 Corinthians 11, Paul points to the many times he had laid his life on the line for Christ for his moral authority to preach the straight and clear messages he preached to those at Corinth. Paul's moral authority to govern the churches and preach the strong messages he preached came from his willingness to lay his life down for the gospel of Christ. If a man desire the office of a bishop, he desireth a good work. Not a novice, lest being lifted up with pride he fall into the condemnation of the devil.
Righteous judgment comes from having a clear conscience.
A pastor's authority to govern a church comes from his willingness to consistently follow the word of God, in his home, in his private life and in his public ministry. God has supplied us with the proper weapons to win that war, and the weapons he has provided are faith in Christ and the word of God and a good conscience. Without that good conscience, our message will not be effective. We will not have the boldness to speak out on issues if we have a guilty conscience. Because we are sinners, we must be assured that our sins are forgiven in Christ, or our conscience will be violated.