They Are To Look To The One Who Has Begotten Them to Eternal Life Through Jesus Christ And Keep Themselves from Sin And From The World (1 John 5:18-20).
‘We know that whoever is begotten of God does not continue in sin, but he who was begotten of God keeps himself (or ‘him'), and the evil one touches him not. We know that we are of God, and the whole world lies in the evil one. And we know that the Son of God is come, and has given us an understanding, that we know him that is true, and we are in him that is true, even in his Son Jesus Christ. This is the true God, and eternal life.'
John concludes by stressing what we can know with assurance. The first thing we can know is that those who are begotten of God do not continue in sin. They hate sin. They long to be rid of sin. They mourn over sin. They bring it to God and agree with His condemnation of it. (1 John 1:9) They seek its removal by cleansing in the blood of Jesus Christ (1 John 1:7). Thus do they keep themselves within His love and His Kingly Rule so that the Evil One cannot touch them. Alternately the meaning may be that ‘He Who was begotten of God keeps him', that Jesus the One Who was uniquely begotten of God acts as his Saviour and Redeemer.
The second thing that we know is that we are of God, while the whole world lies in the Evil One. This was indeed the picture portrayed at Jesus temptations, where the Devil had such unseen power that he could control nations (Matthew 4:8-9). The world thinks that it gets its own way. In fact it is deceived and led along by the Evil One. He is the hidden, but true ruler of this world. It is in his arms. Yet not because of his supreme power, but because man in his foolishness chooses for it to be so. Worldly behaviour and trends and attitudes come because of the deceitful activity of the Evil One. And those who love the world are of him, and can only be delivered by response to Jesus Christ and being begotten of God.
The third thing that we know is that the Son of God is come, and has given us an understanding (through the Spirit) so that we know Him Who is true, in contrast with the deceit and lies of the Devil. We have come to the light. And we have entered into Him Who is true, dwelling in Him Who is true, even in His Son Jesus Christ. Notice the closeness of relationship between Father and Son. To dwell in One is to dwell in the Other. This (the Father and the Son) is the true God, and eternal life.
So he finishes with this huge contrast. On the one hand the world. Lying in the Evil One, (not ‘in him' but as good as), deceived, without understanding, alienated from the life of God through the ignorance that is in them because of the hardness of their hearts (Ephesians 4:18), existing in darkness, dead in trespasses and sins (Ephesians 2:1), lulled into a false sleep. And on the other being in the One Who is true, given understanding, knowing the truth, dwelling in God, and in His Son Jesus Christ, walking in the light (1 John 1:7), enjoying in and through Him eternal life. This is what the true believer has to rejoice in over against the false ‘believer', the fact that he has life, spiritual understanding and knowledge of God. Indeed this last situation is the reason for the final exhortation.