We must place our trust solely on Him as our only Savior, and on no other, not on ourselves or our own opinions, however good they may be. Do not trust yourself to your own opinions, but take them to Christ and see whether they are in conformity with the faith (Romans 12:2) and the Word of the holy Gospel. I, too, occasionally have beautiful and splendid thoughts, and I believe that the Holy Spirit inspired them. But when I judge them in the light of faith, I realize that they are sheer filth, sinful and impure. Therefore it is essential for the heart of a Christian to be firmly convinced that Christ’s innocent life, His holy blood, and precious death are our salvation, that we, together with all the saints, must cling to Christ alone, and that no saint in heaven ever relied on himself and his own righteousness.
“Sermons on the Gospel of St. John: Chapters 1-4” in Works, 22:272.