Theophylact of Ohrid, on 1John 4:12

“No man hath seen God at any time. If we love one another, God abideth in us, and his charity is perfected in us.”

“We have noted before that the Apostle John has a habit of repeating the same things about the same subjects. So he does now as well. No one, he says, has ever seen God. Speaking of love for the brethren, he pointed to God as an example of love, Who out of love for us delivered His Only-Begotten Son to death. Someone, upon hearing this, might ask: on what basis do you speak of things invisible? In answer to such a question he says: I myself say that no one has ever seen God; but from love for one another we come to know that God is in us. And he says this rightly, because many things invisible to us we come to know from their effects. For example, no one has seen the soul, but from its actions and movements we are convinced that it exists and operates within us. So too we recognize God's love for us through a certain movement and action. If there is nothing incongruous in this, then this holy man also fittingly proves from the action that God is in us. What then is this action? Pure love for our neighbors.”

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