Hello, and thank you very much for taking the time to address my question. What a blessing your site is!
I am a member of the church of Christ. My brother was raised in the church, but he is no longer devout and hasn't been for many years. My brother cheated on his wife. Despite his wife's attempts to reconcile for well over a year, he lied continuously and never stopped seeing the other woman. I talked with both my brother and sister-in-law for several months and encouraged them to reconcile. Despite all efforts, my brother left his wife and children and chose to pursue the relationship with the other woman. He is now living with her and is not yet divorced, and has even introduced his children to her.
I have decided that I will not attend events where both he and his mistress are present. I love my brother, and I pray continuously that he will restore his marriage and family. I feel that if I act like everything is fine and treat her welcomingly, I will be condoning their sinful relationship that has brought turmoil upon his family.
Am I honoring God in this decision? I have been criticized by others pretty harshly in my decision. Thank you again for your time.
I'm not surprised by the reactions of others. Worldly people don't think anything is wrong and even among the religious there is a strong desire to avoid conflicts. "Blessed are those who are persecuted for righteousness' sake, For theirs is the kingdom of heaven. Blessed are you when they revile and persecute you, and say all kinds of evil against you falsely for My sake. Rejoice and be exceedingly glad, for great is your reward in heaven, for so they persecuted the prophets who were before you" (Matthew 5:10-12).
The problem is that your brother is a fallen Christian (I assume he was a member at one point in his life). "I wrote to you in my epistle not to keep company with sexually immoral people. Yet I certainly did not mean with the sexually immoral people of this world, or with the covetous, or extortioners, or idolaters, since then you would need to go out of the world. But now I have written to you not to keep company with anyone named a brother, who is sexually immoral, or covetous, or an idolater, or a reviler, or a drunkard, or an extortioner -- not even to eat with such a person" (I Corinthians 5:9-11). Your brother and his mistress are showing contempt for God and in the process are destroying the lives of others. Do things with your nieces and nephews. Stay in contact with your sister-in-law. But leave your brother's mistress out of your life. Keep your interaction with your brother to the minimum that you can manage. Be polite, but make it clear that the barrier between you and him is due to his sins.