v29: “not discerning the Lord’s body”: the usual Protestant interpretation applies this to failing to discern the Lord’s body in the bread and wine of the Lord’s Supper, which is a spiritual activity.
It is contrasted with the Roman Catholic doctrine of transubstantiation, so that the Westminster Shorter Catechism in its question What is the Lord’s Supper? answers: “The Lord’s supper is a sacrament, wherein, by giving and receiving bread and wine according to Christ’s appointment, his death is showed forth; and the worthy receivers are, not after a corporal and carnal manner, but by faith, made partakers of his body and blood, with all his benefits, to their spiritual nourishment and growth in grace.” The phrase “not after a corporal and carnal manner” is in contrast to the Roman Catholic doctrine of transubstantiation and the Lutheran doctrine of consubstantiation. The emphasis is thus put upon discerning “by faith” Christ’s body and blood in the bread and wine.
However, has this debate focused our attention on the completely wrong thing? Does Paul not actually mean that by their sectarian attitudes 1Cor 11:21 they were failing to discern that other Corinthian believers were the Lord’s body ? The division among them 1Cor 11:18; 1Cor 1:11-13 manifested itself in their manner of eating separately from each other. They failed to discern other Corinthians as Christian brethren, dividing the body of Christ 1Cor 1:13, and thus Paul says categorically that “this is not to eat the Lord’s Supper” 1Cor 11:20.
Instead of failing to discern by faith the Lord’s body in the bread and wine, does Paul not mean that they failed to discern by faith the Lord’s body in each of the gathered believers? Their faith failed to see this, resulting in a divisive and party spirit and behaviour. This is the context of the passage, as well as the opening chapters of the epistle.
The Lord’s Supper should show the unity of Christian brethren in a congregation. Paul chastises the Corinthians that it highlighted the divisions among them.