I was just reading your answer to a young man about his brother in regard to I Corinthians 5:11. My husband's family has a similar situation with his older brother. His brother claims to still be a believer but left the fellowship at the church my father-in-law planted due to doctrinal differences. His brother is not worshiping anywhere and from outward appearances, is indulging in drinking parties, getting tattoo's, etc. His facebook page made it clear that he is doing those things although he claims to be living a quiet life, working with his hands as the Lord wants him to, etc.
Some family members refuse to associate with him at all and state I Corinthians 5:9-13 as their reason. They have made it clear that they won't even come to holiday events if that brother is there. I am going to a nephew's graduation party this week, and his mother is the only sibling that associates with that brother now, and I know he will be there. My husband is undecided on where he stands but is leaning toward total disassociation as well. Interestingly enough, their parents still associate with him and intend to still invite him to family and holiday events. My in-laws are some of the most stable Christians I know, and I choose to follow their example, but it has caused problems between some of us. My heart is broken, but I still plan on attending the graduation party because it is about my nephew and his accomplishment, not family differences. I don't plan on socializing or inviting that brother over anytime soon. I just don't want to avoid family events where he will be there as the other sibling are. Are my husband's siblings wrong? Is there scriptural reason for me to say those verses don't apply in my brother-in-laws case as well? Remember, he has stopped worshiping at the church with his family all on his own. But he still claims to be a believer.
I look forward to your answer and am grateful I found you online.
When a person is withdrawn from, and your family is correct that your brother-in-law is not behaving as a Christian ought to behave and must be withdrawn from, a person might have multiple ties and obligations. A person might be withdrawn from, but he might be someone you work with. You can't cut your work obligations, but you can cut your social obligations.
Your sister-in-law and your in-laws really should not be inviting your brother to family gatherings. There is no obligation for him to be there. I understand the motivation. There are people who think withdrawal is too cruel or that they can do some "good" by keeping the door open. Sadly, all they accomplish is a prolonging of a person's deception that they are perfectly fine continuing as they have been. However, you can't control what your in-laws do. You can talk to them about it and encouragement them to be a better example, but they will make up their own minds.
Now, when I find myself in similar situations, what I do is look at why I'm there. For example, one time a sister wanted to have everyone over for a potluck, but her nephew, who lived with her, was withdrawn from. We went for the sister's sake, but every one ignored the nephew (who ended up staying downstairs) except to ask when was he going to come back to Christ. I think he stayed downstairs just to avoid the questions. If he tried to sit down to eat with some of us, we had planned to get up and move to another table, but we didn't have to do that. If you and your husband decide to go, you can use the same tactic.
Your in-laws won't like it, but what will eventually happen is that they won't invite you and your brother-in-law at the same time simply because they don't want the tension.