Albert Barnes Commentary 1 John 3:8

"he that doeth sin is of the devil; for the devil sinneth from the beginning. To this end was the Son of God manifested, that he might destroy the works of the devil." — 1 John 3:8 (ASV)

He that committeth sin. Habitually, wilfully, characteristically.

Is of the devil. This cannot mean that no one who commits any sin, or who is not absolutely perfect, can be a Christian, because this would exclude the great majority—even according to the belief of those who hold that the Christian may be perfectly holy—from all claim to the Christian character.

But what the apostle here says is true in two senses:

1. That all who commit sin, even true believers, to the extent that they are imperfect, in this regard resemble Satan and are under his influence, since sin, to the very extent that it exists at all, makes us resemble him.

2. All who habitually and characteristically sin are of the devil. The latter was evidently the principal idea in the apostle's mind. His object here is to show that those who sinned—in the way that some, it seems, maintained God's children could sin—could have no real evidence of piety but really belonged to Satan.

For the devil sinneth from the beginning. This refers to the beginning of the world, or from the first account we have of him. It does not mean that he sinned from the beginning of his existence, because he was made holy like the other angels .

The meaning is that he introduced sin into the universe and has continued to practice it ever since. The word sinneth here implies continued and habitual sin. He did not commit one act of sin and then reform; rather, he has continued, and still continues, his course of sin.

This may confirm what has already been said about the kind of sin to which John refers. He speaks of sinning habitually, continuously, wilfully; and anyone who does this shows that he is under the influence of him whose characteristic it has been and is to sin.

For this purpose the Son of God was manifested. He became incarnate and appeared among men (1 John 3:5; compare 1 Timothy 3:16).

That he might destroy the works of the devil. This includes all his plans of wickedness and his control over the hearts of men (Hebrews 2:14).

The argument here is that as the Son of God came to destroy all the works of the devil, one who lives in sin cannot be His true follower.