“It is an infallible truth that no person is righteous unless he believes in God, as stated in Rom. 1 [:17]: ‘He who through faith is righteous shall live.’ Likewise, ‘He who does not believe is condemned already” [John 3:18] and dead. Therefore, the justification and life of the righteous person are dependent upon his faith. For this reason all the works of the believer are alive and all the works of the unbeliever are dead, evil, and damnable, according to this passage: ‘A bad tree cannot bear good fruit. Every tree that does not bear good fruit is cut down and thrown into the fire’ [Matt. 7:18-19].” Martin Luther, “Proceedings at Augsburg 1518,” Luther’s Works, vol. 31, p. 270 [Emphasis added] 
On October 31, 1518 Martin Luther returned to Wittenberg from a meeting in Augsburg. Approximately two weeks earlier he had stood before the papal legate, Cardinal Thomas Cajetan. There Luther had refused to recant his teachings on indulgences, grace, and faith unless Cajetan could convince him to do so on the basis of Holy Scripture. In the quote above Luther explained what he had said to Cajetan regarding the nature of faith in relation to grace, salvation, and good works. Here we see Luther asserted what had become the central issue of debate: justification by faith. He continued:
“Faith, however, is nothing else than believing what God promises and reveals, as in Rom. 4 [:3], ‘Abraham believed God, and he reckoned it to him as righteousness’ [Cf. Gen. 15:6]. Therefore the Word and faith are both necessary, and without the Word there can be no faith, as in Isa. 55 [:11]: ‘So shall my word be that goes forth from my mouth; it shall not return to me empty.” Ibid., 271.
