"You cannot drink the cup of the Lord and the cup of demons" (1 Cor. 10:21).
Paul’s exhortation for the Corinthians to be watchful arose out of the question whether it was lawful to eat the sacrifices offered to idols. The apostle, while admitting that there was nothing wrong in eating such meat, urged the Corinthians to abstain for the sake of their weaker brethren.
There was, however, another reason for this abstinence. As a wise shepherd should, Paul knew his flock. He knew the temptations that could easily beset them even when they knew it not. He warns them to abstain from idolatrous feasts because they might be led into idolatry. By going to the edge of that which is permissible, they might be drawn into sin. There was great danger that the Corinthians, convinced that an idol was nothing, might be induced to join the sacrificial feasts that took place within the temples. It was one thing to buy meat at the market and then eat it in their homes, but it was quite another to actually go to the feasts themselves. Paul tries to convince them that going to sacrificial feasts was the same as engaging in idolatry.
The apostle argues his point from analogy. “Attendance on the Lord’s Supper is an act of communion with Christ, the object of Christian worship, and with all those who unite with us in the service,” Hodge wrote. “From its very nature, it brings all who partake of the bread and wine into fellowship with Christ and with one another, vs. 14–17. The same is true of Jewish sacrifices. Whoever eats of those sacrifices is thereby brought into communion with the object of Jewish worship. The act is in its nature an act of worship, v. 18. The conclusion is too plain to need being stated—those who join in the sacrificial feasts of the heathen, join in the worship of idols. Such is the import of the act, and no denial on the part of those who perform it can alter its nature.” It is not to be inferred, however, that the objects of heathen worship are real gods. Partaking of an idol-feast is an act of heathen worship, but it does not make Jupiter or Juno real beings as Christ is. Far from it. What the heathen sacrifice, they sacrifice to demons. Therefore, to partake of their sacrifices was to be brought into communion with demons and thus out of communion with Christ.
Read Deuteronomy 32:16–43. Israel had rebelled against God by worshiping idols. What was God’s response? What does this passage reveal about the character of God? Is God still jealous for His people now that the Gospel has been proclaimed? (1 Cor. 10:22) Carefully examine your life for any trace of idolatry. Confess it to God today.