'Idol' in the Bible

Therefore concerning the eating of things sacrificed to idols, we know that no idol is anything in the world, and that there is no other God but one.

However, that knowledge isn't in all men. But some, with consciousness of the idol until now, eat as of a thing sacrificed to an idol, and their conscience, being weak, is defiled.

What am I saying then? That a thing sacrificed to idols is anything, or that an idol is anything?