Romans 14:15
For if your brother is hurt [spiritually] by [your eating a certain] food, you are no longer acting lovingly [toward him]. Do not destroy [spiritually] the person Christ died for by what you eat.
Galatians 1:8-9
However, if we [apostles] or even an angel [claiming to be] from heaven were to preach any other "gospel" than the one we have [already] preached to you, let that person be cut off from God's [salvation].
Galatians 5:12
I wish that those who are causing such a problem over wanting people to be circumcised would just mutilate themselves [while they are at it!].
2 Timothy 4:14
Alexander the metal worker did me much harm; the Lord will repay him for what he did.