1 Corinthians 10:21

You cannot drink [both] the cup of the Lord and the cup of evil spirits [i.e., and still be acceptable to God]. You cannot share in [both] the Lord's table and the table of evil spirits [and still be acceptable to God].

Matthew 6:24

No person can serve two masters, for he will either hate the one and love the other, or else he will cling to the one and look down on the other. You cannot serve God and material things [at the same time].

1 Corinthians 8:10

For if someone with a weak conscience sees you, who have [correct] knowledge [in this matter], eating in an idol's temple, will he not be encouraged to eat food sacrificed to idols?

1 Corinthians 10:16

Does not the "cup of blessing," which we bless, signify a fellowship with Christ's [physical] blood? [Note: This was the cup used at the close of the Passover meal and was called this because of the prayer of thanksgiving offered for it. Paul refers to such a prayer in connection with its use in the Lord's Supper]. Does not the bread that we break signify a fellowship with Christ's [physical] body?

2 Corinthians 6:15-17

And what harmony can Christ have with Belial? [Note: "Belial" means "worthlessness" and was used for referring to the devil]. Or, what does a believer have in common with an unbeliever?

Treasury of Scripture Knowledge

Summary

Ye cannot drink the cup of the Lord, and the cup of devils: ye cannot be partakers of the Lord's table, and of the table of devils.

Bible References

Cannot drink

1 Corinthians 10:16
Does not the "cup of blessing," which we bless, signify a fellowship with Christ's [physical] blood? [Note: This was the cup used at the close of the Passover meal and was called this because of the prayer of thanksgiving offered for it. Paul refers to such a prayer in connection with its use in the Lord's Supper]. Does not the bread that we break signify a fellowship with Christ's [physical] body?
1 Corinthians 8:10
For if someone with a weak conscience sees you, who have [correct] knowledge [in this matter], eating in an idol's temple, will he not be encouraged to eat food sacrificed to idols?
Matthew 6:24
No person can serve two masters, for he will either hate the one and love the other, or else he will cling to the one and look down on the other. You cannot serve God and material things [at the same time].
2 Corinthians 6:15
And what harmony can Christ have with Belial? [Note: "Belial" means "worthlessness" and was used for referring to the devil]. Or, what does a believer have in common with an unbeliever?