"On Preaching" from the Confessions (#23)

In the preaching of the law there are two things we must always keep in mind. First, we cannot keep the law unless we have been reborn by faith in Christ, as Christ says (John 15:5), “Apart from me you can do nothing.” Secondly, though men can at most do certain outward works, this universal statement must be permitted to interpret the entire law (Heb. 11:6), “Without faith it is impossible to please God.” We must keep the Gospel promise that through Christ we have access to the Father (Rom. 5:2). It is clear that we are not justified by the law. Otherwise, if the preaching of the law were enough by itself, why would Christ and the Gospel be necessary? Thus in the preaching of penitence it is not enough to preach the law, the Word that convicts of sin. For the law works wrath; it only accuses; it only terrifies consciences. Consciences cannot find peace unless they hear the voice of God, clearly promising the forgiveness of sins. Therefore it is necessary to add the Gospel promise, that for Christ’s sake sins are forgiven and that by faith in Christ we obtain the forgiveness of sins. If our opponents exclude the Gospel of Christ from the preaching of penitence, they deserve to be regarded as blasphemers against Christ. (Tappert, The Book of Concord. Fortress Press: Philadelphia, 1959, p.144; Apology IV: 256-7)