You cannot drink the cup of the Lord, and the cup of demons: you cannot be partakers of the Lord's table, and of the table of demons.
All Commentaries on 1 Corinthians 10:21 Go To 1 Corinthians 10
Ambrosiaster
AD 400
Anyone who drinks the cup of demons insults the cup of Christ, and anyone who eats at the table of demons revolts against the table of Christ, that is to say, the altar of the Lord, and crucifies his body again. Commentary on Paul’s Epistles.