During the Protestant Reformation, the magisterial Reformers differed with the Roman Catholic Church over matters including the doctrine of justification, biblical authority, and the Lord's Supper. Although some have claimed that Rome has changed her views on these matters and that the disagreements no longer matter, a study of Rome's official teaching reveals otherwise. Regarding the Lord's Supper, there are two major concerns with Rome's view that are addressed in question and answer 80 of the Heidelberg Catechism.
The first concern is that Roman Catholicism denies the once-for-all sacrifice of Christ in its understanding of the Lord's Supper. Roman Catholics celebrate the sacrament in the Mass, wherein the giving of the bread and the wine is seen as the representation of Jesus' sacrifice to the Father. Protestants often say that Christ is offered up as a sacrifice for human sin again in the Mass, although this is not how official Roman Catholic documents tend to describe the service in our day. It is hard to conclude, however, that Rome does not view the Mass as a re-sacrifice of Jesus, at least in some sense. Paragraph 1367 of the Catechism of the Catholic Church reads: "The sacrifice of Christ and the sacrifice of the Eucharist are one single sacrifice. . . . In this divine sacrifice which is celebrated in the Mass, the same Christ who offered himself once in a bloody manner on the altar of the cross is contained and is offered in an unbloody manner." Rome may see the Mass as an "unbloody" sacrifice, but they see it as a sacrifice nonetheless.
This view is problematic because it denies the once-for-all nature of the death of Jesus. Whether the Mass is the same sacrifice as the sacrifice of Calvary or a brand-new offering of Christ whenever the Mass is celebrated, the end result is the same: Jesus' sacrifice is seen as being continually offered. This denies what the book of Hebrews and, indeed, the entire New Testament says about our Lord's death. It was a one-time event precisely because Christ's death atoned fully and finally for sin. It was not like the old covenant sacrifices that had to be repeated on a daily basis because they could not take away sin. "Christ appeared once for all at the end of the ages to put away sin by the sacrifice of himself" (Heb. 9:26). To suggest otherwise is to call into question the sufficiency of Jesus' atonement and remove any hope we have of salvation.
If Christ's sacrifice of Himself was insufficient to save us and must be offered again and again, then we have no hope of salvation. A sacrifice that has to be repeated is a weak and ineffectual sacrifice that cannot atone for sin or break its power in our lives. Thanks be to God, our Lord's atonement was a once-for-all atonement. It is powerful and effectual to save, and if we trust in Christ alone, our sins are fully and finally covered for all eternity.