The Office of FaithXII. Here, then, is the place to discuss the third thing in the sacrament, i. e., faith, to wit, that a man should firmly believe all this; viz., that this sacrament not only signifies death and the resurrection at the Last Day, by which man is made new for an everlasting, sinless life; but also that it assuredly begins and effects this, and unites us with God, so that we have the will to slay sin, even till the time of our death, and to fight against it; on the other hand, that it is His will to be merciful to us, to deal graciously with us, and not to judge us with severity, because we are not sinless in this life until purified through death. Thus you understand how a man becomes in baptism guiltless, pure and sinless, and yet continues full of evil inclinations, so that he is called pure only because he has begun to be pure, and has a sign and covenant of this purity, and is always to become more pure. Because of this God will not count against him the impurity which still cleaves to him, and, therefore, he is pure rather through the gracious imputation of God than through anything in his own nature; as the Prophet says in Psalm xxxii, "Blessed is he whose transgression is forgiven; blessed is the man unto whom the Lord imputeth not iniquity."[1]
This faith is of all things the most necessary, for it is the ground of all comfort. He who has not this faith must despair in his sins. For the sin which remains after baptism makes it impossible for any good works to be pure before God. For this reason we must hold boldly and fearlessly to our baptism, and hold it up against all sins and terrors of conscience, and humbly say, "I know full well that I have not a single work which is pure, but I am baptised, and through my baptism God, Who cannot lie, has bound Himself in a covenant with me, not to count my sin against me, but to slay it and blot it out."
XIII. So, then, we understand that the innocence which is ours by baptism is so called simply and solely because of the mercy of God, which has begun this work in us, bears