The intimate dispositions of Jesus toward God and His relations with Him are of the utmost importance to us. Jesus is the Son of God; herein lies all His greatness and holiness. By His very nature, He is the only Son of God; we who are made to His image, have become children of God by His mediation. This divine sonship, which belongs to Him by nature, is communicated to us by grace; hence, like Him, all our greatness and holiness consist in our living as true children of God. Therefore, as far as is consistence with our human nature, we should try to reproduce in ourselves the interior attitude of Jesus toward His heavenly Father.
First of all, we note an attitude, or rather a state, of intimate union. It is as the Word that Jesus declares, "The Father is in Me, and I in the Father" (Jn. 10:38). He is referring, of course, to the substantial, incommunicable union of the Word with the Father, which no one can ever imitate; this union is the prerogative of the Son of God alone. But He also made the statement as Man, because, as Man, all His love is concentrated on the Father and dominated by the Father. His whole mind is directed toward Him in an effort to please Him. This union of Jesus with His divine Father is the mode for our union, precisely because it is a union of grace. Grace in Jesus is "infinite," in the language of the theologians, and in this respect it differs from ours; yet even the grace we possess enables us to keep our souls directed toward the Father and our affections centered in Him. Jesus gives us the example Himself, and asks of the Father this close union for us: "As Thou, Father, in Me and I in Thee; that they also may be one in Us" (Jn. 17:21)....
O Jesus, what great treasures are hidden in Your words: "As Thou, Father, in Me, and I in Thee; that they also may be one in Us!" It is not enough for us to imitate Your exterior life; You want more than that. You want us to imitate, as far as mere creatures can, Your interior life, Your intimacy and Your unceasing union with the Father! It would be folly and arrogant temerity even to think of doing this, had You not commanded us to do so. But You have commanded it, and these words of Yours are particularly sacred because they form part of Your last prayer to Your Father, a prayer which contains Your spiritual testament.... (Divine Intimacy, pp. 169, 171)
The key to Christian unity is the all-consuming desire for union with God our Father. When our desire is fixed on God, seeking only Him, and giving Him permission to go into those areas where we can't even discern our own intentions and desires, and mess with us, then we are on the path of being one in Christ with other believers who also are inflamed with this same desire. And those believers who are not yet aflame, but who struggle with weeds and rocks and beaten-down paths? Jesus calls them too and we all journey up the mountain of holiness. Who desires God wholeheartedly who once did not desire Him but half-heartedly?
In this week of prayer for Christian Unity, let's allow ourselves to be caught on fire by one another, with the fire of desire for God and God alone.