3:6 neither known him. John had just noted that there is no one that “sinneth not’ (I John 1:8,10) and obviously would not contradict himself by saying that no one who sins has known God. Two solutions can be suggested to what looks at first like an inconsistency. The believer has two natures—the old man and the new man (Colossians 3:9,10; Romans 7:16-17,22-25). When he lapses into sin, it is not his new man, but the old man, since, as far as His new nature is concerned, “[God’s] seed remaineth in him: and he cannot sin, because he is born of God” (I John 3:9). The second possibility is that the words “abideth” and “sinneth” represent habitual action, not rigidly constant without exception. The verbs are in the continuing present tense, and so with later verses to the same effect (e.g., I John 3:7-10).

3:8 from the beginning. The devil was “a murderer from the beginning,” as well as “a liar and the father of it” (John 8:44).

3:8 was manifested. The Son of God was “manifested to take away our sins” (I John 3:5) and also was manifested to “destroy the works of the devil.” See also Hebrews 2:14; Revelation 20:10.