Augustine of Hippo, on 1John 4:21

“And this commandment we have from God, that he, who loveth God, love also his brother.”

“And now I make it good by another proof. This same apostle hath said, "He gave us commandment that we should love one another." How canst thou be said to love Him whose commandment thou hatest? Who shall say, I love the emperor, but I hate his laws? In this the emperor understands whether thou love him, that his laws be observed throughout the provinces. Our Emperor's law, what is it? "A new commandment give I unto you, that ye love one another." Thou sayest then, that thou lovest Christ: keep His commandment, and love thy brother. But if thou love not thy brother, how canst thou be said to love Him whose commandment thou despisest?”

Imported from an open dataset — not yet checked against the printed edition.