He that committeth sin is of the devil; for the devil sinneth from the beginning. For this purpose the Son of God was manifested, that he might destroy the works of the devil [1 John 3:8].

“He that committeth sin is of the devil.” We need to recognize that the Devil is the source of all sin. He is the one who is responsible for sin being brought into the world. He is the one who led our first parents into sin. And the reason that you and I have a sinful nature today is because of the Devil. “He that committeth sin is of the devil.” Remember that the Lord Jesus said to the religious rulers of His day, “Ye are of your father the devil, and the lusts of your father ye will do …” (John 8:44). The interesting thing is that we will take after our father. If your father is the Devil, then you are going to act like him. If your father is our heavenly Father, then you have His nature, and you are going to act like Him.
“For the devil sinneth from the beginning”—that is, he started out sinning, and he has been at it ever since. He is in rebellion against God.
“For this purpose the Son of God was manifested, that he might destroy the works of the devil.” Only Jesus Christ can deliver you, my friend. Go to Him. Don’t come to me because I cannot help, and no one else can either. But He can, He is the Great Physician, and I urge you to go to Him with your problem.
The Lord Jesus Christ died for the sin of the world. John the Baptist said, “… Behold the Lamb of God, which taketh away the sin of the world” (John 1:29). He took away the penalty of sin. Since you’ve trusted Christ, your sins are behind you, and you are saved in Him. Your sins will never again be brought up as far as your salvation is concerned because you have trusted Him. But John tells us here that the Lord Jesus not only takes away our sin, but He also was manifested to take away our sins—plural. He was without sin—He had no sin nature. “For such an high priest became us, who is holy, harmless, undefiled, separate from sinners …” (Heb. 7:26). But He was a human being, and He died as our sin offering, paying the penalty for our sin. But John also says back in verse 5 of this chapter that He was “manifested to take away our sins.” The word our is not in the better manuscripts; it is literally “manifested to take away sins”—that is, to take away the sins of all believers. In other words, He died to make it possible for you and me to live the Christian life.
This brings us right to the subject of this section from verse 4 to verse 24: every believer has two natures. This is what Paul talks about at length in Romans 7. He says there, “For the good that I would [the desire of this new nature that I have] I do not [that is, the old nature which has been in control so long takes over]: but the evil which I would not, that I do” (Rom. 7:19). The new nature desires to do good, but the old nature drags its feet. The old nature will not serve God; it is in rebellion against God. Paul writes further, “Because the carnal mind is enmity against God: for it is not subject to the law of God, neither indeed can be. So then they that are in the flesh cannot please God” (Rom. 8:7–8). You cannot please God until you are born again. “But ye are not in the flesh, but in the Spirit, if so be that the Spirit of God dwell in you”—there is no idea of a condition here, but rather Paul is saying, since “that the Spirit of God dwell in you. Now if any man have not the Spirit of Christ, he is none of his” (Rom. 8:9). Let me be very clear that we are talking about born–again believers. We are not talking about professing Christians; we are not talking about church members; we are not talking about those that have simply been baptized without ever having been saved; we are not talking about those that go through a ritual or belong to some system. We are talking about those that have been born again. The Lord Jesus was manifested “that he might destroy the works of the devil,” to make it possible for you and me to live for God. McGee, J. V. (1991). Thru the Bible commentary: The Epistles (1 John) (electronic ed., Vol. 56, pp. 94–96). Nashville: Thomas Nelson.

3:8 He who sins. This phrase means “who habitually practice sin” (see notes on vv. 4, 6). of the devil. The phrase gives the source of the false teachers’ actions. The term “devil” means “accuser” or “slanderer.” Not only does Satan (“adversary”) oppose God and his plan, but is the originator and instigator of sin and rebellion against God and His law (v. 4; see notes on Eph. 6:10–17). Therefore, all the unsaved are under the diabolic influence of Satan. Their sinful lifestyle reflects their satanic origin (see note on Eph. 2:1). John contrasts the children of God with the children of Satan in terms of their actions. While those who are truly born again reflect the habit of righteousness, Satan’s children practice sin. from the beginning. Since Satan was originally created as perfect and only later rebelled against God (Is. 14:12–14; Ezek. 24:12–17), John probably means the moment of his rebellion against God, the beginning of his rebellious career. Since sin characterizes him completely, so everyone characterized by sin must derive from him (cf. John 8:44). For this purpose … that He might destroy. A third reason why Christians cannot practice sin is because Christ came to destroy the works of the arch-sinner, Satan. The devil is still operating, but he has been defeated and in Christ we escape his tyranny. The day will come when all of Satan’s activity will cease in the universe and he will be sent to hell forever (Rev. 20:10). works of the devil. This summarizes a variety of the devil’s activities: sin, rebellion, temptation, ruling the world, persecution and accusation of saints, instigation of false teachers, power of death (e.g., Luke 8:12; John 8:44; Acts 5:3; 1 Cor. 7:5; 2 Cor. 4:4; Eph. 6:11, 12; 1 Thess. 2:18; Heb. 2:14; Rev. 12:10). MacArthur, J., Jr. (Ed.). (1997). The MacArthur Study Bible (electronic ed., p. 1969). Nashville, TN: Word Pub.