1 John 3:6

Whosoever abideth in Him sinneth not; whosoever sinneth hath not seen Him, neither known Him.

Here the apostle shows that deliberate, malicious sinning is incompatible with the new life of the Christians: Every one that commits sin commits also lawlessness, and sin is lawlessness. That the apostle makes a distinction between sins of malice and those of weakness, such as come upon a person unawares, is seen from chap. 2:1. Of the former he speaks in this passage. Every one that is in the habit of committing sins thereby places himself in lasting opposition to the Law of God. He commits lawlessness, he deliberately does the opposite of that which the holy will of God demands of all men; he performs what God hates, what He has threatened to punish with temporal death and eternal damnation

Now it is true, in general, with regard to the sins of all men: And you know that He was manifested to bear our sins, and sin is not in Him. This is the gist of the Gospel-message, the great truth with which all believers are familiar. Christ was manifested. He came into the world. He appeared in the fullness of time in order to bear and take away our sins, to atone for all the sins of all mankind, to offer Himself as a perfect sacrifice of propitiation for all time. The handwriting which was against us has been completely wiped out through the salvation of Christ. His sacrifice had such infinite worth because in Him there is no sin; He is the innocent Lamb of God, His blood, as that of the holy Son of God, is the complete price of ransom for all the guilt that was heaped up before the just God.

From this fundamental fact it follows: Every one that remains in Him does not sin; every one that sins has not seen Him nor known Him. Our knowledge of the salvation of Christ is a living knowledge, a living faith. It is through this faith that we have fellowship with Christ, that we are and remain in Christ. In this union the Christian as such does not sin, he refuses to serve sin, he keeps his heart, mind, and thoughts away from sinful things, he will not yield his members to be servants of unrighteousness, Romans 6:1. On the other hand, every one that persists in sin, in lawlessness, in opposition to God's holy will thereby give evidence that he has not seen nor known Christ by faith. If a person is in any way a willing servant of sin and still tries to persuade himself and others that he is a Christian, he is merely deceiving himself. Note; These words of the apostle do not state, as the so-called perfectionists claim, that a Christian here on earth will reach a stage in which he, in his own person, is sinless. Because we still have our sinful nature to contend with, therefore we Christians are prone to stumble and even to fall. It is according to the new man that we are pure in the sight of God, for the sake of Christ's righteousness; it is according to our regenerated self that we do not commit sin and keep all our members in subjection unto holiness. But our carnal self, the old Adam, transgresses the will of God in countless instances, thus imposing upon us the duty to wage incessant warfare against it, as St. Paul has so clearly pictured it, Romans 7:14.