John has reminded his readers of the dangers posed by their enemies – sin and the devil. Here he writes that the new birth brings about an effective deliverance from sin and from the devil. Believing in Jesus is the initial evidence that a sinner has been born again by the work of the Spirit. But the Spirit continues to live within each believer and this indwelling has certain inevitable effects, and one effect is that saved sinners cease living sinful lives and become holy.
The Holy Spirit is here called God’s seed who lives within each regenerated sinner. Since the Spirit as God is omnipotent, his purpose will be achieved; and since he is present to maintain and increase spiritual life, he will bring forth such life in those sinners.
This reality should be of great comfort for believers because it means that Jesus is working in them through another divine person, the Holy Spirit. When they see the deep roots that some sins have in their inner lives they may become prone to despair, and rightly so if the removal of those sins depended on them. But in their great love, the persons of the Trinity are at work, changing their sinful people into holy men and women.
These believers may not see much of the change because sometimes their assessment can be skewed by a current experience of difficulty. Yet others can often see the change: they observe Christlikeness, heavenly-mindedness, and Spirit-filled behaviour. As John writes in verse 10, ‘By this it is evident who are the children of God, and who are the children of the devil: whoever does not practice righteousness is not of God, nor is the one who does not love his brother.’
What should this teaching about the Christian and the devil say to us? First, it should remind us that we face a powerful, subtle foe, who we ignore at our peril.
Second, it reminds us of the necessity of looking to Christ. This is the constant message of the New Testament, not only for justification and glorification, but also for sanctification. have died, and your life is hidden with Christ in God. When Christ who is your life appears, then you also will appear with him in glory.’
Third, this teaching reminds Christians that the quality of their lives reveals whether or not the Holy Spirit, as Christ’s Agent, is working within them. They will not, as a rule, engage in sinful practices. This is not a claim to sinless perfection, but it is a reminder that spiritual renewal will take place in each of them.