Problems related to the Lord's Supper have appeared throughout church history. We have seen some of the faulty understandings of Christ's presence in the supper, but it is worth noting that some of these understandings have led to significant errors in practice. To this day, for example, Roman Catholicism encourages the adoration of the host—the bread in the Lord's Supper—which is an idolatrous practice since a more biblical view asserts that the bread is just that—bread. Also, Roman Catholic theology traditionally describes the Mass as a repetition of the sacrifice of Christ. Yet that violates the New Testament emphasis that Christ was sacrificed once for all (Heb. 10:10).
But errors associated with the Lord's Supper are not merely the province of the post-Apostolic church. Even during the Apostolic era, believers were failing to understand the supper, and they were committing all manner of sins related to the sacrament. Some members of the church in Corinth, for example, mixed idolatry with their celebration of the supper (1 Cor. 10:1–22). Others failed to grasp the nature of the Lord's Supper as a sacrament designed to encourage unity and love among believers. They came to the Lord's Table and gorged themselves on the elements and other foods that were eaten in conjunction with the combined Lord's Supper–fellowship meal or "love feast" observed in the early church (11:17–34). In fact, one of the key reasons the Apostle Paul wrote 1 Corinthians was to correct the church's practice and understanding of the Lord's Supper.
One of the most important principles for celebrating the Lord's Supper rightly is laid out in 1 Corinthians 11:29–30, which tells us that if we eat and drink without "discerning the body," we eat and drink judgment on ourselves. Christ does not take the misuse of His supper lightly, and those who do not partake in faith and repentance risk their very lives. That is why the Reformed tradition stresses that ministers should fence the table whenever the Lord's Supper is celebrated. People should be warned that they dare not take the Lord's Supper if they are not believers or if they are under discipline from a gospel-preaching church and have been barred from the supper. Yes, the Lord's Table is for sinners, but only for sinners who have trusted Christ alone for salvation and are following Him as His disciple in a life of repentance. Only repentant sinners are welcome to the supper.
Christ has not instituted His sacraments for perfect people but for men and women who are sinners. But those who come to the table must be repentant sinners who do not take the sacrament lightly. Let us examine ourselves before we go to the table and repent of our sin so that we may not eat and drink judgment on ourselves.