Perseverance

The Apostle himself in Rom. 6 & 7 shows quite openly that concupiscence is sin properly so called: for not only does he often call it sin, but not good, evil, to be held in hatred, fighting against the law of God, to be crucified, mortified, and destroyed, and rendering that man miserable in whom it resides.

Moral corruption fighting against the law, for the crucifying and mortifying of which Christ himself died on the cross, if it be not properly sin, then Scripture has not explained to us what the property of any habitual sin is.

Every spark of fire is fire, and will burn; so is every thing of the law of sin, the last, the least of it, -- it is enmity, it will poison, it will burn. … Mortification abates of its force, but doth not change its nature. Grace changeth the nature of man, but nothing can change the nature of sin. Whatever effect be wrought upon it, there is no effect wrought in it, but that it is enmity still, sin still.

This corruption of nature, during this life, doth remain in those that are regenerated (1 John 1:8, 10; Rom. 7:14, 17–18, 23; James 3:2; Prov. 20:9; Eccl. 7:20); and although it be, through Christ, pardoned and mortified; yet both itself, and all the motions thereof, are truly and properly sin (Rom. 7:5, 7–8, 25; Gal. 5:17).

The corruption of nature, during this life, does remain in those that are regenerated (Rom. 7:18, 23; Eccl. 7:20; 1 John 1:8); and although it be through Christ pardoned and mortified, yet both itself, and the first motions thereof, are truly and properly sin (Rom. 7:23–25; Gal. 5:17).

Union with Christ is the foundation of all spiritual blessings, so that if there had been no connection with Him, there could be no regeneration, no justification, no sanctification, no glorification. It is so in the natural world—adumbrating the spiritual: sever one of the members from my physical body, and it is dead; only by its union with my person does it partake of life.

The way to get holy endowments and qualifications necessary to frame and enable us for the immediate practice of the law, is to receive them out of the fullness of Christ, by fellowship with Him; and that we may have this fellowship, we must be in Christ, and have Christ Himself in us, by a mystical union with Him.

It is an INDISSOLUBLE union. Once in Christ, ever in him. Having taken up his habitation in the heart, he never leaves. None can untie this happy knot.

And, as our natural corruption was produced originally in the first Adam, and propagated from him to us, so our new nature and holiness is first produced in Christ, and derived from Him to us, or as it were propagated. So that we are not at all to work together with Christ, in making or producing that holy frame in us, but only to take it to ourselves, and use it in our holy practice, as made ready to our hands.

True sanctification is the result of the soul's union with the holy Jesus, the first and immediate receptacle of the sanctifying Spirit; out of whose fullness, his members do, by virtue of their union with him, receive sanctifying influences. The other is the mere product of the man's own spirit, which, whatever it has, or seems to have, of the matter of true holiness—yet does not arise from the supernatural principles, nor to the high aims and ends thereof: for, as it comes from self, so it runs out into the dead sea of self again; and lies as wide of true holiness, as nature does of grace. They who have this species of holiness, are like common boatmen, who serve themselves with their own oars: whereas the ship bound for Immanuel's land, sails by the blowings of the divine Spirit.

The end of Christ's incarnation, death and resurrection was to prepare and form a holy nature and frame for us in Himself, to be communicated to us by union and fellowship with Him; and not to enable us to produce in ourselves the first original of such a holy nature by our own endeavours.

Christ your Head is risen, therefore you cannot be lost: nay, he is not only risen from the dead himself, but is also "become the first-fruits of them that slept," 1 Cor. 15: 20. Believers are his members, his fulness, he cannot therefore be complete without you: a part of Christ cannot perish in the grave, much less burn in hell. Remember, when you feel the natural union dissolving, that this mystical union can never be dissolved: the pangs of death cannot break this tye.