I have a question concerning 1 Cor. 5:9-11 about not associating with believers who behave in certain ways. My brother is not a born again Christian, but we are witnessing to him, and yet his live-in girl friend claims to be a Christian. They both go out and get drunk etc. Should we not even associate with them because of that verse?
Your brother’s girlfriend is obviously not being a good witness, but you shouldn’t assume that she is truly a believer. And even if she is, most Christians are never taught about living in a way that’s pleasing to the Lord and why it’s good to do so.
The main issue is your brother. You’re trying to bring him to the Lord. It wouldn’t make sense to abandon that effort because of his behavior. Paul said it’s God’s kindness that leads us toward repentance (Romans 2:4). First comes salvation, then comes discipleship, and after that, accountability. You can’t expect people to live by the Lord’s standards if they don’t know what His standards are and why they’re important to Him.