John Chrysostom : "For God called us not for uncleanness, but in sanctification." Because he had said "his brother," and had also added, that God is the avenger, showing that even if an unbeliever has suffered this, he who has done it shall suffer punishment, he says, it is not as avenging him that He punishes thee, but because thou hast insulted Himself. He Himself called thee, thou hast insulted Him who called thee. — Homily on 1 Thessalonians 5