Different Unions
Sometimes theologians have spoken about there being three great unions in the Christian faith.
The unity in the Trinity
The union of Christ’s two natures
The believer’s union with Christ
While true! there is also clearly a distinction between how these unions work. In the following passage, Thomas Goodwin looks at John 17 and seeks to highlight the uniqueness of the Son’s union with the Father.
First, Jesus makes clear He has a peculiar union with the Father.
“In his saying, ‘that they be one, as I in thee, and thou in me,’ verse 21, observe, he says not either ut sint in te unum, sicut ego in te unum sum, that they may be one in thee, as I am one in thee. No; but that they may be one in us, as I in thee, and thou in me, he therein entertaining and reserving still an union as peculiar to himself. Nor he says not, that ‘thou mayest be one in us,’ as involving and reckoning himself but as one of them and their rank, and we all one in thee. No, but he says, ‘As thou in me, and I in thee’ (it as a creature is separating), ‘and they one in us’; whereby he manifestly separates himself from them, and betakes himself to a peculiar union and interest with God above them.”
Second, even when we are at height of our union, there is a distance between our union and His and we are completely dependent on Him for it.
The repetition of it a second time, verse 23 (which I most observe), is put there by way of caution, and as with a wariness that that union of himself and his Father be kept inviolate: ‘I in them, and thou in me, that they may be made perfect in one.’ As if he had said, When they arrive to their highest perfection of union, yet let them know, (1.) their distance, that I am above them in it, ‘I in them, and thou in me’; (2.) their dependence and derivation of it from me, ‘I in them, and thou in me.’ And this still continueth, ‘that so they may be perfected in one’; he speaks it not, nor would allow it them upon any other terms. As if he should have said, When they are at their height of union, thou art not, nor ever canst be in them with that immediate union thou art withal in me, and I in thee; I must come in as a middle between them and thee, when they are with us in glory.
Third, in heaven, we are going to be filled up with the Father’s love, but that love will be mediated to us through Christ, meaning we don’t receive God’s love the same way Christ does nor do we become God or Christ.
The descent is, ‘The glory thou hast given me, I have given them,’ ver. 22; they hold of me even then, ‘I in them, thou in me,’ and this is their highest perfection. Yea, at the last verse, when he prays his Father's love might be in them filling them, his prayer, you see, is not only that God's love may be to them, but in them; for the height of our union is the fulness of God communicated in love; as Eph. iii. 19, ‘And to know the love of Christ which passeth knowledge, that ye might be filled with all the fulness of God.’ There is first love, then all the fulness of God mentioned; for heaven is but a communication of God in love; yet even there Christ will needs step in between, even God's love in the communication of it, ‘and I in them.’ The love of God is not so in us, so that we become the love of God; nor is God or Christ so in us, as we become God or Christ; nor is Christ left out when God communicates himself in the highest manner.
Fourth, Jesus clearly wants us to understand how this union works. Christ’s union with God is immediate, and our union is through Christ. He is careful in how he speaks of this union so that we don’t ever leave Him out. Whether God be in us, it is because Christ in us or if Christ be in us and we are one, it is because God is in Christ.
But, as Paul saith, ‘herein is your calling,’ so say I of this: here is the descent of that union on them—God one with Christ, and you with God in Christ. Yea, I observe further his caution in this great point to be such, that if, in praying for our oneness, he mention himself first, he will needs bring in his Father's being in him; so ver. 23, ‘I in you.’ Is not that enough to make them perfect in one? No— but ‘thou in me.’ Again, if he mention his Father's love first, as verse the last, he comes in himself. He turns it every way. So that whether God be in us, it is because Christ is in us; or Christ be in us, and so we one, it is because God is in Christ.
Fifth, Christ’s union is present and perfect. He doesn’t need to pray for it. His union as the Son with the Father is natural. His human nature was united with the divine nature, at once, as a grace to the human nature, not as grace to the person of the divine Son, it was a condescension for Him. Our union on the other hand did need to be prayed for, depends on grace, will be perfected because of grace.
Lastly, which is Ambrose his note: nos unum erimus, sed Pater et Filius unum sunt. He speaks of that union of himself and his Father as already in being and perfection, yea, as that which he then needed not to pray for, and which never needed praying for by him; but he prays that we may be one. He prays not that his Father and he should be one, for they were as fully one already as for ever they could be—to be sure, as second person naturally, and as man, it was so bestowed at once for ever, as it needed no praying for anew; for though it was a grace at first, yet to the divine person that the man was now one withal, it was none; yea, it was a condescending in him, the second person, to match so low as his own speech, when he was to assume it, imports, Heb. x. 5, ‘a body hast thou fitted me.’ He speaks diminutively of it, and yet assumes it.
But that the saints shall be one with this high and mighty us, this us—this is, and was with Christ, a matter of, and subject for, prayer; and this at this time, when yet they were united unto Christ already, as this text implies; for this of ours depends for ever on grace, not so that of Christ's human nature. But once the union being made, transit in jus, it then becomes a right, though at first it was the highest grace to that nature. For why? He is thereby advanced to be the natural Son of God.
Finally, our union is amazing and is patterned after Christ’s union, but definitely different than His union with the Father.
And whereas the word, that they may be one, as we are one, is urged by some for sameness or oneness of union in kind, it is evident by all that hath been spoken, that it is but unio similitudinis, of imitation and similitude, or perhaps of causality, because we are one. The instances of which latter are so frequent I need not mention any of them; as, ‘be perfect, as your heavenly Father is perfect,’ ‘forgive us, as we forgive,’ as we use the speech in the Lord's prayer.”
