"We know that no one who is born of God sins; but He who was born of God keeps him, and the evil one does not touch him. We know that we are of God, and that the whole world lies in the power of the evil one." (1 John 5:18-19)At first blush, this verse is also difficult to understand and to accept. I know that I have been born of God yet, from time-to-time, I still sin. So how can John say that those born of God do not sin? Fortunately, we only have to look back a little way in John's letter to understand what he is saying. John previously said, "No one who is born of God practices sin." (1 John 3:9) John is not saying that, once having been born again we will never stumble in sin, rather he is saying that those who have been born again have laid aside the practice and habit of sin. Temptation may over take us but we no longer sin as a mater of course, habit, or practice.
This change is what is often most immediately apparent to those around us upon our conversion. Peter expresses this same sentiment when he said, "Therefore, since Christ has suffered in the flesh, arm yourselves also with the same purpose, because he who has suffered in the flesh has ceased from sin, so as to live the rest of the time in the flesh no longer for the lusts of men, but for the will of God. For the time already past is sufficient for you to have carried out the desire of the Gentiles, having pursued a course of sensuality, lusts, drunkenness, carousing, drinking parties and abominable idolatries. In all this, they are surprised that you do not run with them into the same excesses of dissipation, and they malign you." (1 Peter 4:1-4) Those who have been united with Christ in His death and resurrection have "suffered in the flesh" and as such have "ceased from sin." They no longer live their lives for the fleeting pleasure of sin but for the eternal pleasures that come from a life lived for God. They no longer live for their own will and pleasure but for the will and pleasure of God.
The reason we can live apart form sin is because of Christ. Darby translates this verse, "he that has been begotten of God keeps himself," (1 John 5:18 Darby) but I believe the above translation to be more accurate, especially when John is comparing the one who keeps us from the one who tempts us. This world lines under the dominion of the evil one. However, we have now chosen new loyalties. However, for a while, must remain and live in his realm even though our allegiances are somewhere else. Before He died, Jesus prayed, "I do not ask You to take them out of the world, but to keep them from the evil one. They are not of the world, even as I am not of the world." (John 17:15-16) Having now ascended, He now keeps us by His power and grace. Our hope of righteousness is no longer in ourselves but in the One who is more than able to keep us.
The evil one can try, but he can no longer assert his dominion over us. Jesus said of Satan, "the ruler of the world is coming, and he has nothing in Me." (John 14:30) The same can be said of us. As we have died to this world so has those things in our lives that Satan once laid claim to. There remains in us nothing that is his. We have been set free. We may be in his kingdom, but we are no longer under his dominion. Thanks be to God!