1 tn The author proclaims in 4:8 ὁ θεὸς ἀγάπη ἐστίν (Jo qeo" agaph estin), but from a grammatical standpoint this is not a proposition in which subject and predicate nominative are interchangeable (“God is love” does not equal “love is God”). The predicate noun is anarthrous, as it is in two other Johannine formulas describing God, “God is light” in 1 John 1:5 and “God is Spirit” in John 4:24. The anarthrous predicate suggests a qualitative force, not a mere abstraction, so that a quality of God’s character is what is described here.
2 tn The ἵνα (Jina) clause in 4:21 could be giving (1) the purpose or (2) the result of the commandment mentioned in the first half of the verse, but if it does, the author nowhere specifies what the commandment consists of. It makes better sense to understand this ἵνα clause as (3) epexegetical to the pronoun ταύτην (tauthn) at the beginning of 4:21 and thus explaining what the commandment consists of: “that the one who loves God should love his brother also.”
3 tn See note on the phrase “fellow Christian” in 2:9.