In a world filled with sin, God does not call us to withdraw from sinners but to shine among them. Yet the Bible draws a clear boundary when one who claims to be a brother chooses an unrepentant lifestyle. This expository study of 1 Corinthians 5:10–13 reveals God’s standard for purity within His house, the believer’s responsibility to judge what happens inside the church, and the call to maintain spiritual integrity without compromise.