Let no man deceive you. That is, in the matter under consideration; to wit, by persuading you that a man may live in sinful practices, and yet be a true child of God. From this it is clear that the apostle supposed there were some who would attempt to do this, and it was to counteract their arts that he made these positive statements in regard to the nature of true religion.

He that doeth righteousness is righteous. This is laid down as a great and undeniable principle in religion -- a maxim which none could dispute, and as important as it is plain. And it is worthy of all the emphasis which the apostle lays on it. The man who does righteousness, or leads an upright life, is a righteous man, and no other one is. No matter how any one may claim that he is justified by faith; no matter how he may conform to the external duties and rites of religion; no matter how zealous he may be for orthodoxy, or for the order of the church; no matter what visions and raptures he may have, or of what peace and joy in his soul he may boast; no matter how little he may fear death, oil hope for heaven -- unless he is in fact a righteous man, in the proper sense of the term, he cannot be a child of God. Compare Mt 7:16-23. If he is, in the proper sense of the word, a man who keeps the law of God, and leads a holy life, he is righteous, for that is religion. Such a man, however, will always feel that his claim to be regarded as a righteous man is not to be traced to what he is in himself, but to what he owes to the grace of God.

Even as he is righteous. See Barnes "1 Jo 3:3".

Not necessarily in this world to the same degree, but with the same kind of righteousness. Hereafter he will become wholly free from all sin, like his God and Saviour, 1 Jo 3:2.

(*) "Little Children" "My Children" {a} "that doeth righteousness" Eze 18:5-9; ro 2:13