sons of God. We can be called “sons of God” because we have been “created in Christ Jesus” (Ephesians 2:10), and are thus “new creatures” in Him (2 Corinthians 5:17). Only those specially created by God (e.g., Adam and the angels—Luke 3:38; Job 38:7) can properly be called “sons of God.” In the last three chapters of this epistle, those who have been thus uniquely “born of God” are said to “not commit sin” (xTerm 3:9), “love one another” (xTerm 4:7), “believeth that Jesus is the Christ” (xTerm 5:1), “overcometh the world” (xTerm 5:4), and “keepeth himself” (xTerm 5:18).

shall be like him. We have been predestined “to be conformed to the image of His Son” (Romans 8:29), because when He comes again, He “shall change our vile body, that it may be fashioned like unto His glorious body” (Philippians 3:21). He will “make all things new” again (Revelation 21:5). Although the Bible does not say specifically, perhaps this means that those who died in old age will be made young again, and those who died in infancy will grow to vigorous maturity, so that all who are Christ's “shall be like Him.”

purifieth himself. The hope of Christ's second coming is not a dead hope, but a “lively hope” (1 Peter 1:3); not a frightening prospect, but a “blessed hope” (Titus 2:13). It is a joyful hope (1 Thessalonians 2:19), a comforting hope (1 Thessalonians 4:13-18), a hope of glory (Colossians 1:27) and an anchoring hope (Hebrews 6:19). Finally, as this verse notes, it is a purifying hope, for it stimulates us to abide in Him.

in him is no sin. On the sinlessness of Christ, see also 2 Corinthians 5:21; 1 Peter 2:22; Hebrews 7:26. Jesus Himself claimed that He always pleased God (John 8:29).

neither known him. John had just noted that there is no one that “sinneth not' (xTerm 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” (xTerm 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., xTerm 3:7-10).

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

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

children of the devil. It is sobering to read that those who are not “children of God” are “children of the devil;” no middle ground is said to exist. They are also called “children of the wicked one” (Matthew 13:38), “children of disobedience” and “children of wrath” (Ephesians 2:2-3). The identification is twofold: those who do not habitually show works of righteousness, and/or those who do not habitually manifest love for other Christians. It is urgent that each one “must be born again” (John 3:3).

from the beginning. The phrase “from the beginning” occurs nine times in the first three chapters of xTerm. That it refers to the “beginning” of Genesis 1:1 is indicated in xTerm 1:1-2: “That which was from the beginning ... was with the Father, and was manifested unto us” (Compare John 1:1-2, 14). This would mean that the command to “love one another” was a new commandment only in its pattern and measure (“as I have loved you,” John 13:34). Love has been at the center of God's plan from the beginning.

Cain. John thus confirms the historicity of the record of Cain and Abel (Genesis 4). Note also Matthew 23:35; Hebrews 11:4; 12:24.

wicked one. Though a child of Adam and Eve, the very first family, Cain was called a child of the devil.

passed from death unto life. Here is another test for knowing whether we are truly saved, and have “passed from death unto life” (John 5:24). See also xTerm 2:3, 5; 3:24; 5:2, 13.

love the brethren. John gives three characteristics of true love for our brethren: doing righteousness (xTerm 3:10); willingness to die for them (xTerm 3:16); willingness to share our possessions with them” (xTerm 3:17).

a murderer. Compare Matthew 5:21-22.

lay down our lives. The meaning here actually is “be laying down.” That is, for our brethren's sake, we ought to serve as a daily “living sacrifice” (Romans 12:1).

seeth. As often seen in this epistle, the verb is in the continuing present—that is, “goes on seeing.” This does not refer to a chance encounter with someone in need, as it would be impossible to help all such, but a continual refusal to help a truly needy fellow Christian with whom we are in frequent contact and who really needs the help we could provide.

not love in word. True love is not something to write or talk about; it is something we do, “in deed and in truth.” Our love for God is demonstrated, not by preaching or singing about it, but by living it. Note xTerm 2:5; 2:15; 5:3. In particular, it will be manifested in our relations with other Christians (xTerm 3:16, 17; 4:11, 20).

we receive of him. Compare xTerm 5:14, 15. A condition for answered prayer is that we pray according to His will and also do according to His will, in so far as we know His will.

he gave us commandment. These two commandments are the most important of all, and they are “not grievous” (xTerm 5:3). In effect, they are essentially another way of stating the two commandments that Jesus said were the greatest of all—loving God and loving our neighbor (see Matthew 22:36-40).

he in him. See John 15:4, 7, 10. We are commanded to abide in Christ, and allow Him to abide in us. We are assured that this is real if we love His words and seek to obey them.

the Spirit. Another assurance of salvation is the indwelling presence of the Holy Spirit (Romans 8:16-17).