A.T. Robertson Commentary 1 John 4:11

"Beloved, if God so loved us, we also ought to love one another." — 1 John 4:11 (ASV)

If God so loved us (ε ουτως ο θεος ηγαπησεν ημας). Condition of first class with ε and the first aorist active indicative. As in Joh 3:16, so here ουτως emphasises the manifestation of God's love both in its manner and in its extent (Romans 8:32).

Ought (οφειλομεν). As in 2:6. Noblesse oblige. "Keep on loving," (αγαπαιν) as in 3:11.