Dr. Martin Luther writes: “Every preacher should exhibit two things. First, a blameless life by which he can defy the world and no one have cause to slander the teaching, and second, irreproachable teaching, that he may mislead none that follow him. So he will be right on both sides: with his good life against the enemies who look much more at his life than at his doctrine; with his doctrine among friends who care more for the doctrine than about his life and will bear with his life for the sake of his teaching.
For it is indeed true that no one lives so perfect a life as to be without sin before God. Therefore it is sufficient that he be blameless in the eyes of the people. But his doctrine must be so good and pure as to stand not only before man but also before God.” (Dobberstein 269)