Jude 1:19

These be they who separate themselves
Not from sinners openly profane; such a separation is commendable, being according to the will and word of God, to the mind and practice of Christ, and which tends to the good of men, and to the glory of God; but from the saints and people of God; it is possible that a child of God may for a time leave the fellowship of the saints, but an entire and total forsaking of them, and of assembling with them, looks with an ill aspect; nor did they separate themselves from superstition and will worship, and every false way of worship, which would have been right, but from the pure worship, ordinances, and discipline of God's house, by a perversion of them, and as being above them, or unwilling to be under any notice and government; not from errors and heresies, and persons that held them, with these they herded; but from the pure doctrines of the Gospel, and ministers of the word, and made divisions and separations among the churches, for worldly ends, and through pride and affectation of vain glory, as if they were more knowing, more holy, and more spiritual than other men: when they were

sensual;
such as gave themselves up to sensual lusts and pleasures; and at best were but natural men, who had only natural and rational abilities, but without spiritual and experimental knowledge: hence it follows,

having not the Spirit;
though they might have some external gifts of the Spirit; or he himself dwelling in them as a spirit of conviction and illumination, as a spirit of regeneration and sanctification, as a spirit of faith and comfort, as a spirit of adoption, and as the earnest and pledge of the heavenly glory; they were not under his influence, nor did they feel the operations of his grace, nor had they communion with him: hence they appeared to be none of Christ's, nor could they claim interest in him, and were without life, and so could not persevere.