'Communion' in the Bible

The cup of blessing which we bless, is it not a communion of the blood of Christ? The bread which we break, is it not a communion of the body of Christ?

Behold Israel after the flesh: have not they that eat the sacrifices communion with the altar?

But I say , that the things which the Gentiles sacrifice, they sacrifice to demons, and not to God: and I would not that ye should have communion with demons.