Jude 1:21

Keep yourselves in the love of God
By which may be meant either the grace and favour of God, that love with which God loves his people; and then the exhortation to the saints to keep themselves in it is, to set it always before them, to keep it constantly in view, to exercise faith on it, firmly believing their interest in it; as also to meditate on it, give themselves up wholly to the contemplation of it, and employ their thoughts constantly about it, which is the foundation of all grace here, and glory hereafter; or to preserve themselves by it, for so the words may be rendered, "preserve yourselves by the love of God"; against Satan's temptations, the snares of the world, and the lusts of the flesh; whenever Satan solicits to sin, and any snare is laid to draw into it, and the flesh attempts to be predominant, saints should betake themselves to the love of God, as to a strong hold and preservative against sin, and reason as Joseph did, ( Genesis 39:9 ) , for the love of God, and continuance in it, do not depend on anything that can be done by men; nor is there any danger of real believers falling from it, or losing it, since it is unchangeable, and is from everlasting to everlasting; or else by the love of God we are to understand that love with which his people love him and of which he is the object, ( Luke 11:42 ) ; and then the meaning of the exhortation is, that though this grace of love cannot be lost, yet, inasmuch as the fervour of it may be abated, and the people of God grow cold and indifferent in their expressions of it, it becomes them to make use of all proper means to maintain and increase it in themselves and others; such as are mentioned in the context, as conversing together in an edifying way about the doctrines of the Gospel, and praying either separately or together, under the influences of the Holy Spirit, and looking forward for the grace and mercy of Christ unto everlasting life; all which, with many other, things, by the blessing of God, may serve to maintain and revive the grace of love, and blow it up into a flame: though perhaps this phrase may chiefly design that love, peace, and concord, which ought to subsist among saints as brethren, and which they should be careful to preserve; and may be called the love of God, just as the same thing is styled the peace of God, ( Colossians 3:15 ) , because it is what God requires, what he calls unto, which is of him, and is taught by him in regeneration, and what his, love engages to, and without which there is no true love to him; and he takes, love shown to his people as if shown to himself; and this sense is favoured by the context, both by the words in the preceding verse, and in the following ones:

looking for the mercy of our Lord Jesus Christ unto eternal life.
The mercy of Christ may be considered either as past, which was shown in eternity, in his covenant transactions with his Father, in engaging in the cause of his people, in espousing them to himself, and in the care of their persons, grace, and glory; and in time, in assuming their nature, in his tender concern for the bodies and souls of men, in bearing the sins and sorrows of his people, in the redemption of them, and in their regeneration and calling; and there is the present mercy of Christ, in interceding for his people, in sympathizing with them under all their afflictions, in succouring them under all their temptations, in suiting himself, as the great Shepherd, to all the circumstances of his flock; and there is the future mercy of Christ, which will be shown at death, in the grave, and at the resurrection, at the day of judgment, and in the merciful sentence he will pronounce on his people; and this seems to be designed here; the consequent of which, or what is annexed to it, and in which it issues, is eternal life; which is not owing to the works of men, but to the grace of God, and mercy of Christ; eternal life is in him, and is given through him, and to his mercy should men look for it. Christ himself is to be looked for, who will certainly come a second time; and eternal life is to be looked for by him; and this is only to be expected through his grace and mercy; and this is to be looked for by faith, in the love of it, with delight and pleasure, and cheerfulness, with eagerness, and yet with patience.