This is an expression that was commonly used in years past, but is seldom heard today. It refers to someone sinning in such a way and in such a public place or under such circumstances that everyone in the community is aware of it and of the sinner’s membership in the church of Christ.
Not all sins fall into this category. A man who regularly loses his temper and yells at his wife in their own home has violated 1 Peter 3:7 and is therefore guilty of sin, but if it’s known only to the two of them, he needs to ask forgiveness only of her and of God. But if he is so loud that the neighbors hear it, or he does it in the grocery store or some other public place, then he not only has caused the entire community (and there are no secrets in small towns) to think poorly of him, but since they know he is a member of the church, they will think poorly of it as well. Whether there was anything the church could have done to prevent the sin is another point, but none the less, people will have less respect for the church and its members because of that man’s sin.
When a situation like this occurs, the only, way to correct it is for the guilty person, who has sinned publicly and brought reproach upon himself and upon the church, to make a very public confession of the sin, so that no one is left in doubt. It may sometimes require not only a confession before the church, but perhaps a letter to the editor of the newspaper or some other step that will reach the whole community. Humiliating? Yes! But God never said the wages of sin would he low (Romans 6:23), and it’s much better than hearing him say on the day of judgment, “Depart from me, you workers of lawlessness.”
via Nettleton church of Christ