A.T. Robertson Commentary 1 Corinthians 10:21

"Ye cannot drink the cup of the Lord, and the cup of demons: ye cannot partake of the table of the Lord, and of the table of demons." — 1 Corinthians 10:21 (ASV)

Ye cannot (ου δυνασθε). Morally impossible to drink the Lord's cup and the cup of demons, to partake of the Lord's table and the table of demons.

Of the table of the Lord (τραπεζης Κυριου). No articles, but definite idea. Τραπεζα is from τετρα (four) and πεζα (a foot), four-footed. Here

table means, as often, what is on the table. See Lu 22:30 where Jesus says "at my table" (επ της τραπεζης μου), referring to the spiritual feast hereafter. Here the reference is plainly to the Lord's Supper (Κυριακον δειπνον, 1 Corinthians 11:20). See allusions in O.T. to use of the table in heathen idol feasts (Isaiah 65:11; Jeremiah 7:18; Ezekiel 16:18f.; Jeremiah 23:41). The altar of burnt-offering is called the table of the Lord in Mal 1:7 (Vincent).