New Defender's Study Bible Notes
4:8 God is love. Some cults and even some evangelicals misuse this verse, making God essentially synonymous with “love,” denying in effect His other attributes. God is, indeed, a loving God, as attested in a multitude of Scriptures, but also “our God is a consuming fire” (Hebrews 12:29). Furthermore, “God is light, and in Him is no darkness at all” (I John 1:5).
4:9 only begotten Son. See notes on John 1:14 and 1:18.
4:10 propitiation. See I John 2:2. These are the only occurrences (in addition to Romans 3:25) of this particular word. It is used in the sense of a substitutionary sacrifice to satisfy both God’s justice and love.
4:13 Hereby know. This is the last of eight “tests” in I John beginning with the phrase, “Hereby know,” each one providing a means of testing the reality of our saving faith. See I John 2:3,5; 3:16,19,24; 4:2,6,13.
4:14 the Saviour. The Son is not just a savior. He is the Savior! “He that hath not the Son of God hath not life” (I John 5:12).