This is language of the most extravagant paradox. What it really means is very objectionable. Melanchthon is to pray very fervently with the hope of obtaining the Divine assistance against sin, but at the same time he is to sin boldly. This language of the Wartburg is not unlike that in which Luther wrote, from the Castle of Coburg, to his pupil, Hieronymus Weller, when the latter was tempted to despair, to encourage him against the fear of sin (above, p. 175 f.); that letter too was written in anguish of spirit and in a state of excitement similar to what he had experienced in the Wartburg. We might, it is true, admit that, in these words Luther gave the rein to his well-known inclination to put things in the strongest light, a tendency to be noticed in some of his other statements quoted above. On the other hand, however, the close connection between the compromising words and his whole system of sin and grace, can scarcely be denied; we have here something more than a figure of rhetoric. Luther’s endeavour was to reassure, once and for all, Melanchthon, who was so prone to anxiety. The latter shrank from many of the consequences of Luther’s doctrines, and at that time was possibly also a prey to apprehension concerning the forgiveness of his own sins. Hence the writer of the letter seeks to convince him that the strength of the fiducial faith preached by himself, Luther, was so great, that no sense of sin need trouble a man. To have “real, not fictitious, sin” to him, means as much as: Be bold enough to look upon yourself as a great sinner; “Be a sinner,” means: Do not be afraid of appearing to be a sinner in your own sight; Melanchthon is to be a bold sinner in his own eyes in order that he may be the more ready to ascribe all that is good to the grace which works all. Thus far there is nothing which goes beyond Luther’s teaching elsewhere.
The passage is, however, more than a mere paradoxical way of expressing the doctrine dear to him.
Luther, here and throughout the letter, does not say what he ought necessarily to have said to one weighed down by the consciousness of sin; of remorse and compunction we hear nothing whatever, nor does he give due weight and importance to the consciousness of guilt; he misrepresents grace, making it appear as a mere outward, magical charm, by which—according to an expression which cannot but offend every religious mind—a man is justified even though he be a murderer and a libertine a thousand times over. Luther’s own words here are perhaps the best refutation of the Lutheran doctrine of Justification, for he speaks of sin, even of the worst, in a way that well lays bare the weaknesses of the system of fiducial faith.