Last time, we looked at a comment Luther makes in his preface to the 1535 Galatians commentary. Below, as he warms up for the commentary itself, he explains why he is commenting on Galatians again, since he had already done so in 1519.

Significantly, the reason is not because he thinks Paul’s teaching about faith is unknown. In fact, he says (just before the passage I quote), “[B]y the grace of God, Paul in his totality is commonly known to you” (gratia Dei totus Paulus nunc vobis notus ac vulgatus sit). No, it is because, however well known the doctrine of faith is, the Devil is always seeking to cover it up and to replace it with the doctrine of works and traditions.

For Luther, that is to say, the Devil is very, very real, and very much alive. He wants to devour, not just people in the abstract, but “us.” And faith is the only thing that gags him. Not only so, but there is also our own flesh to contend with, as well as “temptations on every side”–one notes here at the outset Luther’s regular maleficent triad of the world, the flesh, and the Devil. For all these reasons, the doctrine of faith must be continually taught–we must be “stuffed” with it (inculcari).

For everything in true religion depends upon it. When it is dead, all is dead. When it is well, all is well–with our souls and with our societies.

…periculum hoc maximum et proximum est, ut diabolus ablata pura fidei doctrina rursus invehat doctrinas operum ac traditionum humanarum. Valde prodest igitur, ut haec fidei doctrina in publico et assiduo usu legendi et audiendi conservetur. Et quantumvis cognoscatur et perdiscatur, tamen diabolus adversarius noster semper obambulans et quaerens nos devorare non est mortuus; et caro nostra adhuc vivit; denique omnes undique tentationes nos urgent et premunt. Quare haec doctrina nunquam satis tractari et inculcari potest. Ea iacente et pereunte iacet et perit simul tota cognitio veritatis. Ea vero florente florent omnia bona, religio, verus cultus, gloria dei, certa cognitio omnium statuum et rerum.

[T]his is the greatest and most imminent danger: that the Devil, once the pure teaching of faith has been wiped out, will again bring in its place teachings about works and human traditions. It is, therefore, very advantageous for this teaching about faith to preserved in public by the constant repetition of both reading and hearing. And, however much it is known and thoroughly learned, the Devil, our adversary, who is always prowling about and seeking to devour us, is nevertheless not dead; and our flesh still lives; and, finally, all temptations provoke and oppress us on every side. For that reason, this teaching can never be treated and stuffed into us enough. When it lies sick and dying, all knowledge of the truth lies sick and dying with it. But when it flourishes, all good things flourish–religion, true worship, the glory of God, and the certain knowledge of all estates and affairs.

Martin Luther, Commentarius in Epistolam ad Galatas, Praefatio (WA 40.1, 39). The translation is my own.