Ye cannot drink the cup of the Lord and the cup of devils: ye cannot be partakers of the Lord's table and Ye cannot drink the cup of the Lord, and the cup of devils: ye cannot be partakers of the Lord's table, and of the table of devils.
Ye cannot ... - really, though ye may outwardly (1 Kings 18:21.)
Cup of devils - in contrast to the cup of the Lord. At idol feasts libations were made from the cup to the idol first, then the guests drank; so they had fellowship with the idol. Bread and a cup were used in initiating into the mysteries of Mithras (Justin Martyr).
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 in the same relation analogically to Christ's sacrifice as the Jews' sacrificial feasts did to their sacrifices (cf. Malachi 1:7, "altar ... table of the Lord"), and the pagan idol feasts to theirs (Isaiah 65:11). Heathen sacrifices were to idol nonentities, behind which Satan lurked. The Jews' sacrifice was a shadow of the substance to come. Our one sacrifice of Christ is the only substantial reality. The partaker of the Jews' sacrificial feast partook rather "of the altar" (1 Corinthians 10:18) than of GOD; the pagan idol-feaster had fellowship with demons; the communicant in the Lord's supper has in it a symbolic representation of, and a real fellowship in, the body of Christ once sacrificed, and now exalted as the Head of redeemed humanity.