Matthew Henry Commentary Jude 1:17-23

"But ye, beloved, remember ye the words which have been spoken before by the apostles of our Lord Jesus Christ; That they said to you, In the last time there shall be mockers, walking after their own ungodly lusts. These are they who make separations, sensual, having not the Spirit. But ye, beloved, building up yourselves on your most holy faith, praying in the Holy Spirit, keep yourselves in the love of God, looking for the mercy of our Lord Jesus Christ unto eternal life. And on some have mercy, who are in doubt; and some save, snatching them out of the fire; and on some have mercy with fear; hating even the garment spotted by the flesh." — Jude 1:17-23 (ASV)

Sensual men separate from Christ and His church, and join themselves to the devil, the world, and the flesh, by ungodly and sinful practices. That is infinitely worse than to separate from any branch of the visible church on account of opinions, or modes and circumstances of outward government or worship. Sensual men do not have the Spirit of holiness, and whoever does not have this Spirit does not belong to Christ. The grace of faith is most holy, as it works by love, purifies the heart, and overcomes the world, by which it is distinguished from a false and dead faith.

Our prayers are most likely to prevail when we pray in the Holy Ghost, under His guidance and influence, according to the rule of His word, with faith, fervency, and earnestness; this is praying in the Holy Ghost. And a believing expectation of eternal life will arm us against the snares of sin: lively faith in this blessed hope will help us to mortify our lusts. We must watch over one another; faithfully, yet prudently reprove each other, and set a good example to all those around us. This must be done with compassion, making a difference between the weak and the willful.

Some we must treat with tenderness. Others save with fear; urging the terrors of the Lord. All efforts must be joined with a decided abhorrence of crimes, and care must be taken to avoid whatever led to, or was connected with, fellowship with them in works of darkness, keeping far from what is, or appears to be, evil.