I have been (slowly) reading through Volume 35 of Luther’s Works (English edition). I came across this gem of a sentence:
Faith, however, is a divine work in us which changes us and makes us to be born anew of God, John 1[:12-13]. It kills the old Adam and makes us altogether different men, in heart and spirit and mind and powers; and it brings with in the Holy Spirit. (p. 370)
This is from his preface to the Book of Romans. I think it breathes fresh life into the Lutheran church, which has often neglected the changing power of God’s grace in us.