It is sufficiently evident, that there is a representative union between Christ and the elect, both from everlasting and in time, which is independent on, and prior to their believing in Him. He represented them as their head in election, and in the covenant of grace, and so He did, when upon the cross, and in the grave, when He rose from the dead, entered into heaven, and sat down at the right hand of God. Hence they are said to be crucified with Him, dead with Him, buried with Him, risen with Him, yea, to be made to “sit together in heavenly places in Christ Jesus.” (Ephesians 1:6)

Now all these several unions take their rise from, and have their foundation in, the everlasting love of Christ to His people; which is the grand original, strong and firm bond of union between Him and them, and is the spring of all that fellowship and communion they have with Him in time, and shall have to all eternity. It is from hence that the Spirit of God is sent down into our hearts to regenerate and renew us, and faith is wrought in our souls by the Spirit. Faith does not give us a being in Christ, or unite us to Him; it is the fruit, effect, and evidence of our being in Christ and union to Him. It is true, indeed, that God’s elect do not know their being in Christ and union to Him, until they believe; then what was before secret is made manifest; and because things are sometimes said to be, when they are only manifested to be, hence the people of Christ are said to be in Christ, when they are made new creatures; “if any man be in Christ, he is a new creature” (2nd Corinthians 5:17). Being a new creature, does not put a man into Christ, but is the evidence of his being there; and without which he neither knows, nor ought he to profess himself to be in Christ: And so likewise, in another place, it is said, “If any man have not the Spirit of Christ he is none of his.” (Romans 8:9)

He may be one of His chosen and redeemed ones, though he has not the Spirit of Christ as yet; but he cannot know this until he has the Spirit of Christ; “for no man can say that Jesus is the Lord, that is, his Lord, but by the Holy Ghost” (1st Corinthians 12:3). The apostle Paul takes notice of some that were “in Christ” before him (Romans 16:7); all God’s elect were chosen together in Christ, not one before another: They had all together a being in Him; but this in conversion is made known to one before another. There are different manifestations of union to different persons, and to the same persons at different times; for which Christ prays, when he says, “that they all may be one, as thou, Father, art in me, and I in thee; that they also may be one in us, that the world may believe that thou hast sent me; and the glory which thou gavest me, I have given them, that they may be one, even as we are one; I in them, and thou in me; that they may be made perfect in one, and that the world may know that thou hast sent me, and hast loved them, as thou hast loved me” (John 17:21-23). The full manifestation of it will be in heaven, when the saints shall be with Christ where He is, and behold His glory, and enjoy uninterrupted communion with Him, as the fruit of their eternal union to Him.

John Gill