“The third incomparable benefit of faith is that it unites the soul with Christ as a bride is united with her bridegroom. By this mystery, as the Apostle teaches, Christ and the soul become one flesh (Eph. 5:31–32).
And if they are one flesh and there is between them a true marriage– indeed the most perfect of all marriages, since human marriages are but poor examples of this one true marriage– it follows that everything they have they hold in common, the good as well as the evil.
Accordingly the believing soul can boast of and glory in whatever Christ has as though it were its own, and whatever the soul has Christ claims as his own. Let us compare these and we shall see inestimable benefits.
Christ is full of grace, life, and salvation. The soul is full of sins, death, and damnation.
Now let faith come between them and sins, death, and damnation will be Christ’s, while grace, life, and salvation will be the soul’s; for if Christ is a bridegroom, He must take upon Himself the things which are His bride’s and bestow upon her the things that are His.
If he gives her His body and very self, how shall He not give her all that is His? And if He takes the body of the bride, how shall He not take all that is hers?”
–Martin Luther, The Freedom of the Christian (1520), in Luther’s Works, Vol. 31: Career of the Reformer I (ed. Jaroslav Jan Pelikan, Hilton C. Oswald, and Helmut T. Lehmann; vol. 31; Philadelphia: Fortress Press, 1999), 31: 351.