About an Evil Pastor and the Sacrament
In the Large Catechism V:14ff. Luther explains that as Christ's lips speak and say, so it is; he cannot lie or deceive. Then he writes the following comforting paragraph conerning the Words Jesus speaks in giving us His body and blood .
Hence it is easy to answer all kinds of questions that now trouble people - for example, whether even a wicked priest can administer the sacrament, and similar questions. Our conclusion is: Even though a scoundrel receives or administers the sacrament, it is the true sacrament (that is, Christ's body and blood), just as truly as when one uses it most worthily. For it is not founded on human holiness but on the Word of God. As no saint on earth, yes, no angel in heaven can make bread and wine into Christ's body and blood, so likewise can no one change or alter the sacrament, even through misuse. For the Word by which it was constituted a sacrament is not rendered false because of an individual's unworthiness or unbelief. Christ does not say, "If you believe or if you are worthy, you have my body and blood," but rather, "Take, eat and drink, this is my body and blood." Likewise, when he says, "Do this" (namely, what I now do, what I institute, what I give you and bid you take), this is as much as to say "No matter whether you are worthy or unworthy, you have here his body and blood by the power of these words that are connected to the bread and wine." Mark this and remember it well.
Luther did not teach here or elsewhere that the Lord's Supper was magic through which we receive the forgiveness of sins whether we believe it or not. Forgiveness of sins, life and salvation given in the Sacrament are received through faith. But even unbelievers who partake receive the true body and true blood - not of course to their salvation but to their judgment and spiritual harm.