the one who practices sin is of the devil; for the devil has sinned from the beginning. The Son of God appeared for this purpose, to destroy the works of the devil.” (1 John 3:8, NASB95)

Even a Marine such as myself can figure out what the “works of the devil” are in this passage: “the one who practices sin is of the devil.”  The next sentence in vs. 9 is: “No one who is born of God practices sin.”  One of the purposes of the appearance of Our Lord Jesus is to destroy the works of the devil which in us is the practice and power of sin in our lives.

Before we come to faith in Christ, we are slaves to sin and to our sinful nature and do not see any reason to “rein in” sin, indeed we would rather feed and coddle sin [especially sins like revenge, gossip, hatred, and enmity] than conquer it.  Jesus has given us the power–through the indwelling Holy Spirit–to not practice sin, this is destroying the works of the devil who wants us to remain enslaved to our appetites and sinful nature.

Here is how Paul describes our lives before Christ and after coming to Christ:

Surely you know that the wicked will not possess God’s Kingdom. Do not fool yourselves; people who are immoral or who worship idols or are adulterers or homosexual perverts or who steal or are greedy or are drunkards or who slander others or are thieves—none of these will possess God’s Kingdom. Some of you were like that. But you have been purified from sin; you have been dedicated to God; you have been put right with God by the Lord Jesus Christ and by the Spirit of our God.” (1 Corinthians 6:9–11, GNB)

The practice of sin is of the devil, the practice of righteousness is given to us by the cross and all that follows in light of the cross.