1 John 3:1-3
1. Behold, what manner of love the Father hath bestowed upon us, that we should be called the sons of God: therefore the world knoweth us not, because it knew him not.
1. Videte (vel, videtis) qualem charitatem dedit nobis Pater, ut filii Dei nominemur: propterea mundus non novit nos, quia non novit ipsum.
2. Beloved, now are we the sons of God, and it doth not yet appear what we shall be: but we know that, when he shall appear, we shall be like him; for we shall see him as he is.
2. Dilecti, nunc filii Dei sumus; et nondum apparuit quid erimus: scimus antera quod si apparuerit, similes ei erimus; quia videbimus eum sicuti est.
3. And every man that hath this hope in him purifieth himself, even as he is pure.
3. Et omnis qui habet hanc spem in eo, purificat seipsum, quemadmodum ille purus est.
1 Behold The second argument is from the dignity and excellency of our calling; for it was not common honor, he says, that the heavenly Father bestowed on us, when he adopted us as his children. This being so great a favor, the desire for purity ought to be kindled in us, so as to be conformed to his image; nor, indeed, can it be otherwise, but that he who acknowledges himself to be one of God's children should purify himself. And to make this exhortation more forcible, he amplifies the favor of God; for when he says, that love has been bestowed, he means that it is from mere bounty and benevolence that God makes us his children; for whence comes to us such a dignity, except from the love of God? Love, then, is declared here to be gratuitous. There is, indeed, an impropriety in the language; but the Apostle preferred speaking thus rather than not to express what was necessary to be known. He, in short, means that the more abundantly God's goodness has been manifested towards us, the greater are our obligations to him, according to the teaching of Paul, when he besought the Romans by the mercies of God to present themselves as pure sacrifices to him. (Romans 12:1.) We are at the same time taught, as I have said, that the adoption of all the godly is gratuitous, and does not depend on any regard to works.
What the sophists say, that God foresees those who are worthy to be adopted, is plainly refuted by these words, for, in this way the gift would not be gratuitous. It behooves us especially to understand this doctrine; for since the only cause of our salvation is adoption, and since the Apostle testifies that this flows from the mere love of God alone, there is nothing left to our worthiness or to the merits of works. For why are we sons? Even because God began to love us freely, when we deserved hatred rather than love. And as the Spirit is a pledge of our adoption, it hence follows, that if there be any good in us, it ought not to be set up in opposition to the grace of God, but, on the contrary, to be ascribed to him.
When he says that we are called, or named, the expression is not without its meaning; for it is God who with his own mouth declares us to be sons, as he gave a name to Abraham according to what he was. 
Therefore the world It is a trial that grievously assaults our faith, that we are not so much regarded as God's children, or that no mark of so great an excellency appears in us, but that, on the contrary, almost the whole world treats us with ridicule and contempt. Hence it can hardly be inferred from our present state that God is a Father to us, for the devil so contrives all things as to obscure this benefit. He obviates this offense by saying that we are not as yet acknowledged to be such as we are, because the world knows not God: a remarkable example of this very thing is found in Isaac and Jacob; for though both were chosen by God, yet Ishmael persecuted the former with laughter and taunts; and Esau, the latter with threats and the sword. However, then, we may be oppressed by the world, still our salvation remains safe and secure.
2 Now are we the sons of God He comes now to what every one knows and feels himself; for though the ungodly may not entice us to give up our hope, yet our present condition is very short of the glow of God's children; for as to our body we are dust and a shadow, and death is always before our eyes; we are also subject to thousand miseries, and the soul is exposed to innumerable evils; so that we find always a hell within us. The more necessary it is that all our thoughts should be withdrawn from the present view of things, lest the miseries by which we are on every side surrounded and almost overwhelmed, should shake our faith in that felicity which as yet lies hid. For the Apostle's meaning is this, that we act very foolishly when we estimate what God has bestowed on us according to the present state of things, but that we ought with undoubting faith to hold to that which does not yet appear.
But we know that when he shall appear The conditional particle ought to be rendered as an adverb of time, when But the verb appear means not the same thing as when he used it before. The Apostle has just said, it does not yet appear what we shall be, because the fruit of our adoption is as yet hid, for in heaven is our felicity, and we are now far away traveling on the earth; for this fading life, constantly exposed to hundred deaths, is far different from that eternal life which belongs to the children of God; for being enclosed as slaves in the prison of our flesh, we are far distant from the full sovereignty of heaven and earth. But the verb now refers to Christ, when, he shall appear; for he teaches the same thing with Paul, in Colossians, where he says,
"Your life is hid with Christ in God: when Christ, who is your life, shall appear, then shall ye also appear with him in glory." (Colossians 3:3,4)
For our faith cannot stand otherwise than by looking to the coming of Christ. The reason why God defers the manifestation of our glory is this, because Christ is not manifested in the power of his kingdom. This, then, is the only way of sustaining our faith, so that we may wait patiently for the life promised to us. As soon as any one turns away the least from Christ, he must necessarily fail. 
The word to know, shews the certainty of faith, in order to distinguish it from opinion. Neither simple nor universal knowledge is here intended, but that which every one ought to have for himself, so that he may feel assured that he will be sometime like Christ. Though, then, the manifestation of our glory is connected with the coming of Christ, yet our knowledge of this is well founded.
We shall be like him He does not understand that we shall be equal to him; for there must be some difference between the head and the members; but we shall be like him, because he will make our vile body conformable to his glorious body, as Paul also teaches us in Philippians 3:21. For the Apostle intended shortly to shew that the final end of our adoption is, that what has in order preceded in Christ, shall at length be completed in us.
The reason that is added may, however, seem inappropriate. For if to see Christ makes us like him, we shall have this in common with the wicked, for they shall also see his glory. To this I reply, that this is to see him as a friend, which will not be the case with the wicked, for they will dread his presence; nay, they will shun God's presence, and be filled with terror; his glow will so dazzle their eyes, that they will be stupefied and confounded. For we see that Adam, conscious of having done wrong, dreaded the presence of God. And God declared this by Moses, as a general truth as to men,
"No man shall see me and live." (Exodus 33:20.)
For how can it be otherwise but that God's majesty, as a consuming fire, will consume us as though we were stubble, so great is the weakness of our flesh. But as far as the image of God is renewed in us, we have eyes prepared to see God. And now, indeed, God begins to renew in us his own image, but in what a small measure! Except then we be stripped of all the corruption of the flesh, we shall not be able to behold God face to face.
And this is also expressed here, as he is He does not, indeed, say, that there is no seeing of God now; but as Paul says,
"We see now through a glass, darkly." (1 Corinthians 13:12.)
But he elsewhere makes a difference between this way of living, and the seeing of the eye. In short, God now presents himself to be seen by us, not such as he is, but such as we can comprehend. Thus is fulfilled what is said by Moses, that we see only as it were his back, (Exodus 33:23;) for there is too much brightness in his face.
We must further observe, that the manner which the Apostle mentions is taken from the effect, not from the cause; for he does not teach us, that we shall be like him, because we shall see him; but he hence proves that we shall be partakers of the divine glory, for except our nature were spiritual, and endued with a heavenly and blessed immortality, it could never come so nigh to God yet the perfection of glory will not be so great in us, that our seeing will enable us to comprehend all that God is; for the distance between us and him will be even then very great.
But when the Apostle says, that we shall see him as he is, he intimates a new and an ineffable manner of seeing him, which we enjoy not now; for as long as we walk by faith, as Paul teaches us, we are absent from him. And when he appeared to the fathers, it was not in his own essence, but was ever seen under symbols. Hence the majesty of God, now hid, will then only be in itself seen, when the veil of this mortal and corruptible nature shall be removed.
Refined questions I pass by: for we see how Augustine tormented himself with these, and yet never succeeded, both in his Epistles to Paulus and Fortunatus, and in the City of God, (2:2,) and in other places. What he says, however, is worthy of being observed, that the way in which we live avails more in this inquiry than the way in which we speak, and that we must beware, lest by wrangling as to the manner in which God can be seen, we lose that peace and holiness without which no one shall see him.
3 And every man that hath this hope He now draws this inference, that the desire for holiness should not grow cold in us, because our happiness has not as yet appeared, for that hope is sufficient; and we know that what is hoped for is as yet hid. The meaning then is, that though we have not Christ now present before our eyes, yet if we hope in him, it cannot be but that this hope will excite and stimulate us to follow purity, for it leads us straight to Christ, whom we know to be a perfect pattern of purity.
 Calvin, like our version, renders tekna, "sons;" but the word would be better rendered "children," "That we should be called the children of God." The passage might be thus paraphrased, "See what great proof of love the Father hath given us, that we should be made the children of God" -- Ed  "When he shall appear," refers to Christ, mentioned in the 28th verse of the last chapter; what intervenes seems to have been parenthetically introduced. This is often the manner of writing found in this apostle. The end of the 8th verse, in this chapter, is connected with the 16th; for the antecedent to ekeinos, he, in the latter verse, is "the Son of God" in the former. [1 John 2:28; 3:8, 16.] -- Ed
 "When he shall appear," refers to Christ, mentioned in the 28th verse of the last chapter; what intervenes seems to have been parenthetically introduced. This is often the manner of writing found in this apostle. The end of the 8th verse, in this chapter, is connected with the 16th; for the antecedent to ekeinos, he, in the latter verse, is "the Son of God" in the former. [1 John 2:28; 3:8, 16.] -- Ed