Jude 1:4

4.For there are certain men crept in unawares. Though Satan is ever an enemy to the godly, and never ceases to harass them, yet Jude reminds those to whom he was writing of the state of things at that time. Satan now, he says, attacks and harasses you in a peculiar manner; it is therefore necessary to take up arms to resist him. We hence learn that a good and faithful pastor ought wisely to consider what the present state of the Church requires, so as to accommodate his doctrine to its wants.

The word παρεισέδυσαν, which he uses, denotes an indirect and stealthy insinuation, by which the ministers of Satan deceive the unwary; for Satan sows his tares in the night, and while husbandmen are asleep, in order that he may corrupt the seed of God. And at the same time he teaches us that it is an intestine evil; for Satan in this respect also is crafty, as he raises up those who are of the flock to do mischief, in order that they may more easily creep in.

Before of old ordained. He calls that judgment, or condemnation, or a reprobate mind, by which they were led astray to pervert the doctrine of godliness; for no one can do such a thing except to his own ruin. But the metaphor is taken from this circumstance, because the eternal counsel of God, by which the faithful are ordained unto salvation, is called a book: and when the faithful heard that these were given up to eternal death, it behooved them to take heed lest they should involve themselves in the same destruction. It was at the same time the object of Jude to obviate danger, lest the novelty of the thing should disturb and distress any of them; for if these were already long ago ordained, it follows that the Church is not tried or exercised but according to the infallible counsel of God. (192)

The grace of our God. He now expresses more clearly what the evil was; for he says that they abused the grace of God, so as to lead themselves and others to take an impure and profane liberty in sinning. But the grace of God has appeared for a far different purpose, even that, denying ungodliness and worldly lusts, we may live soberly, righteously, and godly in this world. Let us, then, know that nothing is more pestilential than men of this kind, who from the grace of Christ take a cloak to indulge in lasciviousness. (193)

Because we teach that salvation is obtained through God’s mercy alone, the Papists accuse us of this crime. But why should we use words to refute their effrontery, since we everywhere urge repentance, the fear of God, and newness of life, and since they themselves not only corrupt the whole world with the worst examples, but also by their ungodly teaching take away from the world true holiness and the pure worship of God? Though I rather think, that those of whom Jude speaks, were like the libertines of our time, as it will be more evident from what follows.

The only Lord God, or, God who alone is Lord. Some old copies have, “Christ, who alone is God and Lord.” And, indeed, in the Second Epistle of Peter, Christ alone is mentioned, and there he is called Lord. (194) But He means that Christ is denied, when they who had been redeemed by his blood, become again the vassals of the Devil, and thus render void as far as they can that incomparable price. That Christ, then, may retain us as his peculiar treasure, we must remember that he died and rose again for us, that he might have dominion over our life and death.