1 John 3:3

And every one that hath this hope in Him, purifieth himself even as He is pure. The Apostle next shows us the way to attain this likeness to Christ. We must put our whole trust in Him. To be like Him in glory, we must strive to be like Him in holiness, in suffering, and in passion. For no one will be like Christ in heaven, who is unlike Him on earth. For it is His to give us grace to lead us to accomplish so arduous a work. "The mercy of God is the ground for hoping" to strive after sanctity. It is not enough to place our hope in God unless we put our hand to the work, and labour together with Him. See Rom. viii. 17; Heb. xii. 14; Matt. v. 8. [Pseudo]-Augustine admirably says (de cognit veræ vitæ, in fin.): "To this highest good the righteous are drawn by one link after another. First faith, then hope, then love, perfected in action, action led on by its intention to the highest good, this again issues in perseverance, which will bring us even to God Himself, the fountain of all good."

Purifieth himself, sanctifieth himself, for sanctity "is freedom from every kind of pollution, the most uncontaminated and most perfect purity." (Dionysius, de div. nom. cap. xii.)

The true sanctity of men consists in purification from sins, and rooting out of vices, as S. Paul says, 2 Timothy 2:21.

Moreover, this cleansing from vices is effected by the implanting and exercise of the contrary virtues, as the rooting out of pride by humility, &c. Sanctity then includes all the virtues with which the soul is sanctified and devoted to God. For that is the meaning of 'sanctus.' Some then explain the word in this sense. Just as Priests and 'Religious' dedicate themselves. And indeed all the faithful in a more imperfect way who are by baptism consecrated to God. See 1 Peter 2:9. And Christ said (Joh 17:19), " I sanctify Myself (I offer myself as a holy victim), that the also may be sanctified in the truth."

S. Gregory Nazianzen says, "What is sanctity? To hold converse with God." And S. Bernard (de Consid. v. 14) says, "Holy affection, which is of two kinds, the fear of God, and holy love, makes a man holy. For a soul which is completely affected by these motives, embraces Him with both its arms, and says, I hold Him and will not let Him go." And he says also (Serm. xxv . inter parvos), "There are three things which make a man holy, simple living, holy deeds, a pious intention," &c. (this is pursued at great length).

As He is holy. See Leviticus 26. and Leviticus 27:28. St. John enforces great sanctity, like the sanctity of God Himself, and continued and daily progress therein, that we may be more and more like Him. See Matthew 5:48.

If thou wishest to be holy, set before thee the pattern of sanctity, the life and passion of the Lord. As St. Ambrose says (de Isaac), "Let every one strip off the filthy wrappings of His soul, and prove it, when cleansed from its filth, as gold in the fire. But the beauty of a soul, when thus cleansed, consists in a truer knowledge of heavenly things, and the sight of that supreme Good from which all things depend, being Itself from nothing." And S. Gregory Nazianzen, "Let us restore to His image its beauty, let us recognise our dignity, follow our pattern, learn the power of the mystery, and for what purpose Christ died. Let us be as Christ, since He became as one of us. Let us be gods for His sake, as He became man for ours." And speaking of God he says, "He holds nothing so precious as purity or cleansing." (Orat. vi.) Ver 4. Whosoever committeth sin, also doeth iniquity, for sin is iniquity. "For whosoever sins," says Bede, "acts contrary to the equity of the Divine Law." The faithful ought to sanctify themselves in order to be like Christ, and on the contrary sin is α̉νομία, a breaking of the Divine Law, and makes us utterly unlike God, and hateful to Him. He means "deadly sin." S. Augustine (contr. Faust. xxii. 7) says, that "sin is anything we say, do, or desire, against the Divine Law." And S. Ambrose (de.Parad. cap. 8), "Sin is disobedience to the Divine commands." In like manner iniquity is a departure from the equity which the law prescribes, and injustice is contrary to justice, and α̉νομία is what is contrary to law. Sin and iniquity mean, in S. John, the same thing, though in popular speech iniquity has a worse meaning than sin. See S. Gregory, Mor. xi. 21. S. Ambrose (Apol. Dav. cap. 13) says the exact contrary, regarding sin as the worse of the two.

But every sin, even against human or ecclesiastical law, is contrary to God, as being contrary to His eternal law, which is the source of all law. As S. Thomas says (1. 2, quæst. 91), "Law is the highest reason existing in the Divine mind, according to which He directs the actions of all creatures to their own proper ends. For as there is in God the reason for His creating things, so also is the law by which they are to be governed. And as the one is the conception in the Divine mind, which decided how they were to be made, so is the other that eternal law, by which every creature should discharge its own functions, together with the will which obliges them, or at least impresses on them an inclination, to follow it.