Isaiah 12 is a canticle fitted for singing in the assembly, employed in Lutheran worship since the Reformation as the natural response to God's saving acts. Its opening verse, “I will give thanks to you, O Lord, for though you were angry with me, your anger turned away, that you might comfort me,” is the precise movement AC XXIV describes as the true purpose of Christian worship: a conscience that has received the gift of forgiveness now gives thanks for what it has received. The song does not earn the comfort; it responds to the comfort already given. Give thanks, make known His deeds, proclaim His name is exalted. This is the sacrifice of praise rendered by those who have already been reconciled.
Psalm 105 models the same form at length. It opens with the summons to give thanks, call upon the name, and make known the deeds among the peoples, then proceeds through the entire history of God's acts: the covenant with Abraham, the sojourn in Egypt, the Exodus, the wilderness provision. Worship here is entirely the recitation and celebration of what God has done, not a presentation of what the worshiper is doing for God. AC XXIV argues this is the form Luther retained and Rome destroyed: a liturgy of thanksgiving for a completed gift, not a sacrificial mechanism for earning further ones.
| Term | What It Means |
|---|---|
| Sacrament vs. sacrifice | The Apology's foundational distinction. A sacrament is a ceremony in which God presents to us what the promise offers; grace moves downward from God to man. A sacrifice is a ceremony in which we render honor to God. The Mass is a sacrament, not a sacrifice. |
| Ex opere operato | By the mere outward act of doing it. The medieval error: the Mass benefits the recipient regardless of faith. AC XXIV rejects this entirely. Without faith, the ceremony profits nothing for salvation. |
| Propitiatory sacrifice | A sacrifice that appeases God's wrath and merits remission of sins. There has been only one such sacrifice: the death of Christ on the cross. The Church cannot re-sacrifice Christ to pay for daily sins. |
| Eucharistic sacrifice | A sacrifice of thanksgiving offered by those already reconciled. Not a work that merits forgiveness, but the praise, prayer, proclamation, and confession rendered by those who have received the free gift. Isaiah 12 and Psalm 105 model this form. |
AC XXIV opens with a sentence that has surprised readers ever since it was first presented: “Falsely are our churches accused of abolishing the Mass; for the Mass is retained among us, and celebrated with the highest reverence.” The Reformers retained the vestments, chants, calendar, and liturgical structure. What they changed was the language, interspersing Latin with German hymns so the unlearned could understand and be taught about Christ. What they removed was the canon's propitiatory language, the prayers that offered Christ's body and blood to the Father as a sacrifice to merit grace for the living and the dead. AC XXIV's defense is that removing this language was not abolition but correction. The liturgy of thanksgiving and reception that remained was the older and more scriptural form, the form Isaiah 12 and Psalm 105 model.
The Apology provides the theological framework AC XXIV presupposes. All sacred works fall into one of two categories. A sacrament is a ceremony in which God presents to us what the promise offers; grace moves toward the person. A sacrifice is a ceremony in which we render honor to God; movement is from the person toward God. The medieval Mass had become a propitiatory sacrifice: a ceremony in which the priest offered Christ's body and blood to the Father to appease divine wrath and merit remission of sins for the living and the dead, applicable by the mere outward performance of the ceremony, without faith.
The Confessions' response is total: there has been only one propitiatory sacrifice in the history of the world, the death of Christ on the cross, and it cannot be repeated. What the Church offers in its assembled worship is therefore a Eucharistic sacrifice: the sacrifice of praise, prayer, thanksgiving, and proclamation rendered by those who have already been reconciled. Isaiah 12's song of the turned-away anger and Psalm 105's recitation of God's acts are both Eucharistic sacrifices in this sense: not payments, but the response of people who have received what they could never earn.
AC XXIV's most pointed historical critique is of the private Mass system. Because the Mass was understood as a work applicable to others, private Masses were multiplied without end for the benefit of the dead. The theological premise was that while Christ's passion covered original sin, the Mass was needed as a daily payment for actual sins, turning it into a commercial transaction between the living and the dead. The Confessions call this base profanation for lucre.
The dismantling required returning to Christ's command: “This do in remembrance of Me.” To remember Christ is to remember His benefits and recognize they are freely offered. The Mass is a medicine to cheer and comfort the anxious conscience, and that cheering is what sacraments do when received by faith. The Confession's practical consequence is direct: without faith, no benefit accrues, not because the gift is withheld, but because a gift that is not received does not function as a gift.
Isaiah 12's song begins with the anger that has turned away and ends with the cry, “Shout and sing for joy, O inhabitant of Zion, for great in your midst is the Holy One of Israel.” The Holy One great in the midst of Zion is the same One whose death was the only propitiatory sacrifice, whose body and blood are the sacrament that cheers and comforts the anxious conscience, and whose command this do in remembrance converts the assembly's response from a transaction into a song.
Isaiah 12's song begins with the anger that has turned away and ends with the cry, “Shout and sing for joy, O inhabitant of Zion, for great in your midst is the Holy One of Israel.” The Holy One great in the midst of Zion is the same One whose death was the only propitiatory sacrifice, whose body and blood are the sacrament that cheers and comforts the anxious conscience, and whose command this do in remembrance converts the assembly's response from a transaction into a song. Psalm 105's great recitation of God's acts is the congregation's Eucharistic sacrifice: the praise of those who have been given everything, rendered back to the One who gave it.