1 Corinthians 5:9-10

9I already wrote a letter to you. I told you that you must not be friends with people who have sex in wrong ways.

10But I was not talking about people who do not know God. Those people have sex in wrong ways. They want many things to please themselves. They deceive people and they rob them. They worship idols. You could not keep away from all people like that, unless you left this world!