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 patiently with sin, and regards us as though we were sinless, This also explains why Christians are called in the Scriptures the children of mercy, a people of grace, and men of God's good-will. [Eph. 5:1, 9] It is because in baptism they have begun to become pure, [Luke 2:14] and by God's mercy are not condemned with their sins that still remain, until, through death and at the Last Day, they become wholly pure, as the sign of baptism shows. Therefore they greatly err who think that through baptism they have become wholly pure. They go about in their unwisdom, and do not slay their sin; they will not admit that it is sin; they persist in it, and so they make their baptism of no effect; they remain entangled in certain outward works, and meanwhile pride, hatred, and other evils of their nature are disregarded and grow worse and worse. Nay, not so! Sin and evil inclination must be recognized as truly sin; that it does not harm us is to be ascribed to the grace of God, Who will not count it against us if only we strive against it in many trials, works, and sufferings, and slay it at last in death. To them who do this not, God will not forgive their sins, because they do not live according to their baptism and covenant, and hinder the work which God and their baptism have begun. [Sidenote: Baptism and Repentance] XIV. Of this sort are they also who think to blot out and put away their sin by "satisfaction," [7] and even regard their baptism lightly, as though they had no more need of it after they had been baptised,[8] and do not know that it is in force all through life, even until death, nay, even at the Last Day, as was said above.[9] For this cause they think to find some other way of blotting out sin, viz., their own works; and so they make, for themselves and for all others, evil, terrified, uncertain consciences, and despair in the hour of death; and they know not how they stand with God, thinking that by sin they have lost their baptism and that it profits them no more.