The cup of blessing - The apostle speaks here of the Eucharist, which he illustrates by the הברכה כוס cos habberacah, cup of blessing, over which thanks were expressed at the conclusion of the passover. See this largely explained at the conclusion of the notes on Matthew 26:75, and in my Discourse upon the Eucharist, 8vo. 2nd edit. 1814.
The communion of the blood of Christ? - We who partake of this sacred cup, in commemoration of the death of Christ, are made partakers of his body and blood, and thus have fellowship with him; as those who partake of an idol feast, thereby, as much as they can, participate with the idol, to whom the sacrifice was offered. This I have proved at large in the above tract, to which I must refer the reader, as the subject is too voluminous to be inserted here.
The cup of blessing which we bless - The design of this verse and the following verses seems to be, to prove that Christians, by partaking of the Lord‘s Supper, are solemnly set apart to the service of the Lord Jesus; that they acknowledge Him as their Lord, and dedicate themselves to him, and that as they could not and ought not to be devoted to idols and to the Lord Jesus at the same time, so they ought not to participate in the feasts in honor of idols, or in the celebrations in which idolaters would be engaged; see 1 Corinthians 10:21. He states, therefore:
(1) That Christians are “united” and dedicated to Christ in the communion; 1 Corinthians 10:16-17.
(2) that this was true of the Israelites, that they were one people, devoted by the service of the altar to the same God, 1 Corinthians 10:18.
(3) that though an idol was nothing, yet the pagan actually sacrificed to devils, and Christians ought not to partake with them; 1 Corinthians 10:19-21. The phrase “cup of blessing” evidently refers to the wine used in the celebration of the Lord‘s Supper. it is called “the cup of blessing” because over it Christians praise or bless God for his mercy in providing redemption. It is not because it is the means of conveying a blessing to the souls of those who partake of it - though that is true - but because thanksgiving, blessing, and praise were rendered to God in the celebration, for the benefits of redemption; see Note, Matthew 26:26. Or it may mean, in accordance with a well known Hebraism, “the blessed cup;” the cup that is blessed. This is the more literal interpretation; and it is adopted by Calvin, Beza, Doddridge, and others.
Which we bless - Grotius, Macknight, Vatablus, Bloomfield, and many of the early church fathers suppose that this means, “over which we bless God;” or, “for which we bless God.” But this is to do violence to the passage. The more obvious signification is, that there is a sense in which it may be said that the cup is blessed, and that by prayer and praise it is set apart and rendered in some sense sacred to the purposes of religion. it cannot mean that the cup has undergone any physical change, or that the wine is anything but wine; but that it has been solemnly set apart to the service of religion, and by prayer and praise designated to be used for the purpose of commemorating the Saviour‘s love. That may be said to be blessed which is set apart to a sacred use (Genesis 2:3; Exodus 20:11); and in this sense the cup may be said to be blessed; see Luke 9:16, “And he took the five loaves and the two fishes, and looking up to heaven he blessed them,” etc.; compare Genesis 14:9; Genesis 27:23, Genesis 27:33, Genesis 27:41; Genesis 28:1; Leviticus 9:22-23; 2 Samuel 6:18; 1 Kings 8:41.
Is it not the communion of the blood of Christ? - Is it not the emblem by which the blood of Christ is exhibited, and the means by which our union through that blood is exhibited? Is it not the means by which we express our attachment to him as Christians; showing our union to him and to each other; and showing that we partake in common of the benefits of his blood? The main idea is, that by partaking of this cup they showed that they were united to him and to each other; and that they should regard themselves as set apart to him. We have communion with one κοινωνία koinōniathat which is in “common,” that which pertains to all, that which evinces fellowship) when we partake together; when all have an equal right, and all share alike; when the same benefits or the same obligations are extended to all. And the sense here is, that Christians “partake alike” in the benefits of the blood of Christ; they share the same blessings; and they express this together, and in common, when they partake of the communion.
The bread - In the communion. It shows, since we all partake of it. that we share alike in the benefits which are imparted by means of the body of the Redeemer. In like manner it is implied that if Christians should partake with idolaters in the feasts offered in honor of idols, that they would be regarded as partaking with them in the services of idols, or as united to them, and therefore such participation was improper.