'Idol' in the Bible

concerning then the eating of things sacrificed to idols, we know that an idol is nothing in the world, and that there is no other God save one.

But knowledge is not in all: but some, with conscience of the idol, until now eat as of a thing sacrificed to idols; and their conscience, being weak, is defiled.

For if any one see thee, who hast knowledge, sitting at table in an idol-house, shall not his conscience, he being weak, be emboldened to eat the things sacrificed to the idol?

What then do I say? that what is sacrificed to an idol is anything, or that an idol is anything?