Heidelberg Catechism – Lord’s Day 30
Q. What difference is there between the Lord’s Supper and the papal Mass?
A. The Lord’s Supper testifies to us that we have compete forgiveness of all our sins through the one sacrifice of Jesus Christ which he himself has accomplished on the cross once for all; (and that through the Holy Spirit we are incorporated into Christ, who is now in heaven with his true body at the right hand of the Father and is there to be worshipped). But the Mass teaches that the living and the dead do not have forgiveness of sins through the sufferings of Christ unless is again offered for them daily by the priest (and that Christ is bodily under the form of bread and wine and is therefore to be worshipped in them). Therefore the Mass is fundamentally a complete denial of the once for all sacrifice and passion of Jesus Christ (and as such an idolatry to be condemned).
Q. Who ought to come to the table of the Lord?
A. Those who are displeased with themselves for their sins, and who nevertheless trust that these sins have been forgiven them and that their remaining weakness is covered by the passion and death of Christ, and who also desire more and more to strengthen their faith and improve their life. The impenitent and hypocrites, however, eat and drink judgment to themselves.
Q. Should those who show themselves to be unbelievers and enemies of God by their confession and life be admitted to this Supper?
A. No, for then the covenant of God would be profaned and his wrath provoked against the whole congregation. According to the ordinance of Christ and his apostles, therefore, the Christian church is under obligation, by the office of the keys, to exclude such persons until they amend their lives.