John Calvin Commentary 1 Corinthians 10:27

"If one of them that believe not biddeth you [to a feast], and ye are disposed to go; whatsoever is set before you, eat, asking no question for conscience` sake." — 1 Corinthians 10:27 (ASV)

If any one of those who do not believe invites you. Here follows an exception, meaning that if a believer has been warned that what is set before him has been offered to an idol, and sees that there is a danger of causing offense, he sins against his fellow believers if he does not abstain. So, he shows, in short, that care must be taken not to hurt weak consciences.

When he says, and you are willing to go, he subtly suggests that he does not entirely approve of it and that it would be better if they declined; but since it is an indifferent matter, he does not choose to forbid it absolutely. And certainly, there could be nothing better than to keep at a distance from such snares — not that those who accommodate themselves to others only as far as conscience permits are to be expressly condemned, but because we ought to proceed with caution when we see that we are in danger of falling.