It is supernatural, being altogether beyond the powers of the creature to effectuate. It is wholly of the wisdom, grace, and power of God. All the unions we have in the natural world come infinitely short of this. The union of the body and soul in man puzzles and baffles the greatest philosophers, but the union of Christ and His Church is a far greater mystery: that persons so distant, so divided, should be made one, is a profundity which no finite intelligence can fully comprehend. We had known nothing whatever about it if God had not revealed it to us in His Word, and even now we discern it “through a glass darkly.”

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.

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.

It is a REAL union. Such is our weakness in our present state, so much are we sunk in sin, that in our mind, we are prone to suspect spiritual realities to be only a fiction. But nothing is more real than what is spiritual: as approaching nearest to the nature of him who is the fountain of all reality, namely, God himself. We do not see with our eyes the union between our own soul and body; neither can we represent it to ourselves truly, by imagination, as we do sensible things: yet the reality of it is not to be doubted. Faith is no fancy—but "the substance of things hoped for," Heb. 11:1. Neither is the union thereby made between Christ and believers imaginary—but most real: "For we are members of his body, of his flesh, and of his bones," Eph. 5:30.

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.