But what else does it mean to be spiritual than to be a child of the Holy Spirit and to have the Holy Spirit? But the Holy Spirit is the Paraclete, the Advocate, the Comforter. When our conscience accuses us, He protects us in the presence of God and comforts us by giving a good testimony to our conscience and to our trust in the mercy of God. He excuses, extenuates, and completely covers our sins. On the other hand, He magnifies our faith and good works. Those who imitate Him in the presence of fellowmen with regard to the sins of their fellowmen are spiritual. Satan, on the other hand, is called the devil, the detractor and calumniator, because he not only accuses us and makes our evil conscience worse in the presence of God but also disparages what is good about us and filifies our merits and the faith of our conscience. He is imitated in the presence of their fellowmen by those who, with regard to the sins or even the good works of their fellowmen, exaggerate, enlarge, and expand the sins of their fellowmen but, on the other hand, minimize, find fault with, and disapprove of their good works. Hence St. Augustine says on this passage [Galatians 6:1]: Nothing so demonstrates the spiritual man as his treatment of someone else’s sin, when he plans how to set him free rather than how to deride him, and how to help him rather than how to revile him. On the other hand, you will demonstrate as carnal the man who deals with someone else’s sin only in order to judge and censure, as the Pharisee insulted the tax collector but had no pity on him.”
Luther, Martin Luther’s Works: volume 27 (Lectures on Galatians 1535. Chapters 5-6; 1519. Chapters 1-6) 388