2 John 1:11
For the person who greets him [with approval] participates in his evil deeds [i.e., in his false teaching].
1 Timothy 5:22
Do not be in a hurry to lay hands on anyone [i.e., to appoint them to office. See 4:14], and do not participate in the sins of other people. [Note: If Timothy failed to carefully determine the qualifications of a prospective elder before appointing him, it would make him partially responsible for any wrongdoing by that elder]. Keep yourself pure [i.e., of involvement in anyone's sins].
Ephesians 5:11
Do not have fellowship with [people who practice] worthless deeds of darkness [i.e., sinful living], but expose them instead.
Revelation 18:4
Then I heard another voice from heaven, saying, "Come out of her, my people, so that you do not share in her sins, and so that you do not receive her plagues [i.e., judgments].