The cup of blessing which we take, does it not give us a part in the blood of Christ? and is not the broken bread a taking part in the body of Christ?
1 Corinthians 10:16
It is not possible for you, at the same time, to take the cup of the Lord and the cup of evil spirits; you may not take part in the table of the Lord and the table of evil spirits.
1 Corinthians 10:21
And he took bread and, having given praise, he gave it to them when it had been broken, saying, This is my body, which is given for you: do this in memory of me.
And in the same way, after the meal, he took the cup, saying, This cup is the new testament, made with my blood which is given for you.
And he said to them, Go into the town to such a man, and say to him, The Master says, My time is near: I will keep the Passover at your house with my disciples.
Father, if it is your pleasure, take this cup from me: but still, let your pleasure, not mine, be done.
For where two or three are come together in my name, there am I among them.