The “if” does not imply doubt or uncertainty, but is John’s characteristic way of impressing truth on his readers’ hearts. The first word translated “know” in this verse is oida, which refers to intuitive knowledge. The second, ginōskō, refers to knowledge gained by experience (see on 1 John 1:3; Rom. 3:19). In this way the apostle connects the believer’s theoretical knowledge with his practical knowledge as the basis for an appeal to righteous living.
He.
Opinion is divided as to whether John here refers to Christ or to the Father. Some, reasoning that the closing phrase “born of him” can refer only to the Father, because John speaks only of the believer’s being “born of God” (chs. 3:9; 4:7; 5:1, 4, 18), claim that the apostle here speaks of the Father. Certainly none will dispute the righteousness of God, and ultimately all who are redeemed have been born of Him (John 1:13). But it is also certain that John has hitherto been speaking of the Son (1 John 2:25, 27, 28), and it is unlikely that he would make such a sudden, unannounced change from the Son to the Father. Christ is righteous, and it is through His power, in cooperation with the Spirit, that the Christian is reborn. Thus it may be that the primary reference is still to the Son.
See on Matt. 5:6. He who is consistently righteous in thought, word, attitude, and deed demonstrates that he is born of God, the One from whom every good thing comes (Matt. 7:20; James 1:17). If such a man continues to permit God to work in him, he will be accorded further instruction until he walks in the full light of Heaven (Prov. 4:18; John 7:17; DA 238; GC 528). However, some are, momentarily, able to present a false appearance of righteousness, which is inspired by self-love (Matt. 6:1-18; 1 Cor. 13:3; 3T 336; SC 18, 28, 29).