It is by the human nature of Jesus Christ that we enjoy union with His divine nature and that He is Emmanuel, God with us. His humanity is the medium by which His divinity communicates itself with all its graces. Under the former dispensation, God communicated with His people through the ark of the covenant, which was a type of the human nature of Jesus Christ, in order to show us that, by it, we have union with the whole of His person. And, by union with the person of Jesus Christ, we obtain communion with the Father. “At that day, ye shall know that I am in My Father, and you in Me, and I in you.”
It is not by nature that we enjoy this union since, by nature, we are “children of wrath” and “without Christ.” The means by which we are united to Christ are, on His part, by His Spirit and, on our part, by faith. He communicates His Spirit to us, which is as the soul that unites all the members of the body with the head, so that “he who is joined unto the Lord is one Spirit.” On our part, we receive Jesus Christ by faith produced in us by His Spirit in order that we may reciprocally receive Him in our hearts. He dwells in our hearts by faith. And thus, we learn what is meant when it is said we are justified by faith, not as being a work or anything meritorious, but as the medium through which His righteousness, and all the graces and blessings that are in Christ Jesus, are communicated to our souls.
From: Exposition of the Epistle to the Romans by Robert Haldane; reprint (Edinburgh: The Banner of Truth Trust, 1958), p. 313. Comment from an exposition of Romans 8.1. Originally published in three volumes (1836-1839).