During His Farewell Discourse, Jesus explained to Philip that to see Him is to see the Father (John 13:8–11). Yet He is not Himself the Father; otherwise, He could not have been the way to the Father (John 14:6). He is also “in” the Father, and the Father is “in him.” This mutual indwelling is, as the theologians say, “ineffable”— beyond our ability to understand. Yet it is not beyond faith’s ability to believe.
Moreover, the Holy Spirit lies at the heart of this bond between the Father and His Son. But now the Father has sent His Son (who is “in” the Father). Such is the love of the Father and the Son for believers that they will come to make believers their home.
How so? The Father and Son come to indwell the believer through the indwelling of the Holy Spirit (14:23). He glorifies Christ (16:14). He takes what belongs to Christ, given to Him by the Father, and shows it to us. Later, when we have the privilege of overhearing our Lord’s prayer, Jesus similarly speaks about the intimacy of fellowship with God that sustained Him so wonderfully: “You, Father, are in me, and I in you” (John 17:21).
This is deep theology indeed. Yet virtually the profoundest statement we can make about God is that the Father is “in” the Son and the Son “in” the Father. It seems so simple that a child can see it. For what word can be simpler than in?
Yet this is also so profound that the best of minds cannot fathom it. For whenever we seek to contemplate the one person of the Father, we find we cannot do so without thinking of His Son (for He cannot be a father without a son). Neither can we contemplate this Son apart from the Father (for He cannot be a fatherless son). All this is possible only because the Spirit illumines who the Son really is as the One through whom alone we can come to the Father.
Thus, our minds simultaneously swell with delight at this threeness in unity and yet are stretched beyond their capacities by the notion of the unity in the threeness. Almost as staggering is the fact that Jesus reveals and teaches all this to be the most life-steadying, poise-giving, heart-comforting, and even joy-giving gospel truth (15:11).
The Trinity is so vast in significance because it can bring comfort to men driven to the edge by the atmosphere of sorrow about to engulf them. The triune One is greater in glory, deeper in mystery, and more beautiful in harmony than all other realities in creation. No tragedy is too big to overwhelm Him; nothing incomprehensible to us is so to Him, whose very being is incomprehensible to us. There is no darkness deeper than the depths of the inbeing of God.
It is perhaps understandable, then, that Jonathan Edwards could write in his Personal Narrative:
God has appeared glorious to me, on account of the Trinity. It has made me have exalting thoughts of God, that he subsists in three persons; Father, Son and Holy Ghost. The sweetest joys and delights I have experienced, have not been those that have arisen from a hope of my own good estate; but in a direct view of the glorious things of the gospel. When I enjoy this sweetness, it seems to carry me above the thoughts of my own estate; it seems at such times a loss that I cannot bear, to take off my eye from the glorious, pleasant object I behold without me, to turn my eye in upon myself, and my own good estate.
But the revelation of the Trinity is in fact related to our “own good estate.”
The Wonder of the Union Disclosed
The point of Jesus’ teaching is not merely to stun our minds or stir our imaginations. It is to give us a sense of the vast privilege of union with Him.
From the very beginning of these few hours of ministry, Jesus had spoken about His disciples having a “share” with Him (John 13:8). He had also explained that the Spirit reveals to Christians that they are “in Christ” and He is in them (14:20). This is a union so real and wonderful that its only real analogy—as well as its foundation—is the union of the Father and the Son through the Spirit. The disciples would enjoy union with the Son and therefore would have fellowship with the Father through the Spirit. “You know him,” said Jesus, “for he dwells with you, and will be in you” (v. 18). These enigmatic words do not refer to the contrast of the relationship between the Spirit and old covenant (“with you”) and new covenant believers (“in you”). They are often understood that way, but Jesus is actually saying: “You know the Spirit, because He is with you in Me, but He will come (at Pentecost) to be in you as the very One who has been My constant companion (and in that sense ‘with you’). As such, He is no other than the One who is the bond of fellowship between the Son and the Father from all eternity.”
Thus, to be united to Christ is to share in a union created by the indwelling of the Spirit of the incarnate Son who Himself is “in” the Father as the Father is “in” Him. Union with Christ means nothing less than fellowship with all three persons of the Trinity. It is not that the divine nature is infused into believers. Our union with Christ is spiritual and personal—effected by the indwelling of the Spirit of the Son of the Father.
Notice, then, the exquisite picture Jesus paints to express the beauty and intimacy of this union: it involves nothing less than the Father and the Son making their home in the heart of the believer (v. 23).
Significantly, Jesus does not require believers to do a dozen things—but only to believe and to love. For it is the realization (“in that day you will know”; v. 20) of the reality and magnitude of this union with God the Trinity through union with Christ that transforms the thinking, feeling, willing, loving, and, consequently, the actions of the believer. In this union, the Father prunes the branches of the vine to bear more fruit (15:2). In this same union, the Son keeps all those the Father has given Him (17:12).
No wonder John Donne prayed:
Batter my heart, three-person’d God; for you As yet but knock; breathe, shine, and seek to mend; That I may rise and stand, o’erthrow me, and bend Your force to break, blow, burn, and make me new. I, like an usurp’d town to another due, Labor to admit you, but oh, to no end; Reason, your viceroy in me, me should defend, But is captiv’d and proves weak or untrue. Yet dearly I love you, and would be lov’d fain, But I am bethroth’d unto your enemy; Divorce me, untie or break that knot again, Take me to you, imprison me, for I, Except you enthrall me, never shall be free, Nor ever chaste, except you ravish me. (Holy Sonnets XIV)