4 For certain men have got in unnoticed, they who of old were marked out beforehand to this sentence, ungodly [persons], turning the grace of our God into dissoluteness, and denying our only Master and Lord Jesus Christ. 5 But I would put you in remembrance, you who once knew all things, that the Lord, having saved a people out of [the] land of Egypt, in the second place destroyed those who had not believed. 6 And angels who had not kept their own original state, but had abandoned their own dwelling, he keeps in eternal chains under gloomy darkness, to [the] judgment of [the] great day; 7 as Sodom and Gomorrha, and the cities around them, committing greedily fornication, in like manner with them, and going after other flesh, lie there as an example, undergoing the judgment of eternal fire.

Matthew Henry's Commentary on Jude 1:4-7

Commentary on Jude 1:1-4

(Read Jude 1:1-4)

Christians are called out of the world, from the evil spirit and temper of it; called above the world, to higher and better things, to heaven, things unseen and eternal; called from sin to Christ, from vanity to seriousness, from uncleanness to holiness; and this according to the Divine purpose and grace. If sanctified and glorified, all the honour and glory must be ascribed to God, and to him alone. As it is God who begins the work of grace in the souls of men, so it is he who carries it on, and perfects it. Let us not trust in ourselves, nor in our stock of grace already received, but in him, and in him alone. The mercy of God is the spring and fountain of all the good we have or hope for; mercy, not only to the miserable, but to the guilty. Next to mercy is peace, which we have from the sense of having obtained mercy. From peace springs love; Christ's love to us, our love to him, and our brotherly love to one another. The apostle prays, not that Christians may be content with a little; but that their souls and societies may be full of these things. None are shut out from gospel offers and invitations, but those who obstinately and wickedly shut themselves out. But the application is to all believers, and only to such. It is to the weak as well as to the strong. Those who have received the doctrine of this common salvation, must contend for it, earnestly, not furiously. Lying for the truth is bad; scolding for it is not better. Those who have received the truth must contend for it, as the apostles did; by suffering with patience and courage for it, not by making others suffer if they will not embrace every notion we call faith, or important. We ought to contend earnestly for the faith, in opposition to those who would corrupt or deprave it; who creep in unawares; who glide in like serpents. And those are the worst of the ungodly, who take encouragement to sin boldly, because the grace of God has abounded, and still abounds so wonderfully, and who are hardened by the extent and fulness of gospel grace, the design of which is to deliver men from sin, and bring them unto God.

Commentary on Jude 1:5-7

(Read Jude 1:5-7)

Outward privileges, profession, and apparent conversion, could not secure those from the vengeance of God, who turned aside in unbelief and disobedience. The destruction of the unbelieving Israelites in the wilderness, shows that none ought to presume on their privileges. They had miracles as their daily bread; yet even they perished in unbelief. A great number of the angels were not pleased with the stations God allotted to them; pride was the main and direct cause or occasion of their fall. The fallen angels are kept to the judgment of the great day; and shall fallen men escape it? Surely not. Consider this in due time. The destruction of Sodom is a loud warning to all, to take heed of, and flee from fleshly lusts that war against the soul, Job 15:16.