Matthew Poole on 1 Corinthians 10:20

The heathens might not intentionally offer sacrifices to devils, (such a thing can hardly be supposed of men), but actually they offered sacrifices to devils; for they were devils, that is, evil angels, which deluded the poor heathen, and gave answers from the images and statues which they worshipped, believing the true God to be in them: which answers they accounted for oracles. Besides, the apostle saith, they sacrificed to devils, because in God’s esteem it was so, though not in their intention; God judgeth of men’s acts of worship and homage pretendedly done unto him, not according to their intention, but according to the truth and reality of the thing: now, really the heathen in their sacrifices paid a homage to devils, though such a thing was far from their intention; and this deserves the consideration, both of the papists, who worship images, and also of those protestants (if any such be) who would excuse the papists in their idolatries from their intentions. The nature of idolatry doth not lie in men’s intending to worship the creature instead of the Creator, (there were hardly every any such idolaters in the world), but in their actual doing of the thing; and except they can find a direct rule in holy writ ordering the adoration of the Creator in the creature, or before the creature, it is much to be feared, that in the last day God will judge their homage performed to the creature, not to him. Now, saith the apostle, you had need take heed that, by this action, you prove not yourselves to have fellowship with devils, instead of Christ and the true and living God.

—Matthew Poole