1 Corinthians 10:21

“Ye cannot drink the cup of the Lord, and the cup of devils, etc.] Not only they ought not, but they could not rightly, truly, and really drink the cup of wine in the Lord’s supper, in the true faith of Christ’s bloodshed, and his sacrifice offered up for them, in remembrance of his love, and to the honour of his name; and also the cup of wine of libations, poured out and drank to the honour of the Heathen deities; these things are utterly inconsistent; no man can serve two masters, God and mammon, or God and Baal; nor is there any concord between Christ and Belial, or agreement between the temple of God and idols: ye cannot be partakers of the Lord’s table, and of the table of devils; no man…”

“Ye cannot drink the cup of the Lord--really and spiritually; though ye may outwardly (Kg1 18:21). cup of devils--in contrast to the cup of the Lord. At idol feasts libations were usually made from the cup to the idol first, and then the guests drank; so that in drinking they had fellowship with the idol. the Lord's table--The Lord's Supper is a feast on a table, not a sacrifice on an altar. Our only altar is the cross, our only sacrifice that of Christ once for all. The Lord's Supper stands, however, in the same relation, analogically, to Christ's sacrifice, as the Jews' sacrificial feasts did to their sacrifices (compare Mal 1:7, "altar . . . table of the Lord"), and the heathen idol feasts…”

“Ye cannot drink the cup of the Lord ... - This does not mean that they had no physical ability to do this, or that it was a natural impossibility; for they certainly had power to do it. But it must mean that they could not “consistently” do it. It was not fit, proper, decent. They were solemnly bound to serve and obey Christ, they had devoted themselves to him, and they could not, consistently with these obligations, join in the worship of demons. This is a striking instance in which the word “cannot” is used to denote not natural but moral inability. And the cup of devils - Demons; 1 Corinthians 10:20. In the feasts in honor of the gods, wine was poured out as a libation, or drank by the…”

“Ye cannot drink the cup of the Lord, and the cup of devils - You cannot have communion with both. 1 Corinthians 10:22”

“10:21 Believers should avoid participating in religious meals eaten in a pagan temple (see 8:10), because those united to the Lord (Christ) cannot simultaneously be united to demons (see 2 Cor 6:14-16).”

“cannot drink: Co1 10:16, Co1 8:10; Deu 32:37, Deu 32:38; Kg1 18:21; Mat 6:24; Co2 6:15-17 1 Corinthians 10:22”