"The fact of the matter is that Jesus is simply no longer present with his people in the physical and local way that he once was; but rather, in this period of overlap between Christ's ascension and second coming, the way his presence is mediated to his people is by the Holy Spirit through the church, an outpost of grace."Really focus is on that phrase "they way his presence is mediated to his people is by the Holy Spirit" and ask, "What does that mean?"
Obviously, we don't encounter Jesus in the a "local" way - he isn't geographically, physically present with us, not even when we're in the sanctuary on a Sunday morning. Christ ascended into heaven and is seated at the Father's right hand in heaven (Acts 1:6-11; Rom. 8:33-34; Heb. 10:11-13). After his ascension, Christ is really, in his flesh and blood, absent from his people. Christ, ever the God-man, is not omnipresent in his flesh and blood. He is, in his humanity, finite.
But, at the same time, Christ promised his presence with us till the end of the age (Matt. 28:20), and that he would be present wherever two or more are gathered in his name (Matt. 28:20). How is this possible? Two common responses leave us a little confused.
First, some might say argue that Christ is present with us in his divine nature, but not with us in his human nature. I think, however, that misses something important. Christ promises his personal presence with us, not simply the presence of his divine nature. Orthodox Christology maintains that in the person of Christ two natures exist "without confusion, without change, without division, without separation; the distinction of natures being in no way annulled by the union, but rather the characteristics of each nature being preserved and coming together to form one person and subsistence, not as parted or separated into two persons, but one and the same Son and Only-begotten God the Word, Lord Jesus Christ; even as the prophets from earliest times spoke of him, and our Lord Jesus Christ himself taught us, and the creed of the fathers has handed down to us" (Definition of Chalcedon). If Christ is with us personally, he must be with us in the fullness of his personhood, which, from the time of his incarnation means both his human and divine natures.
Others might wish to answer that Christ is with us is the Spirit. Yes, but I think we have to be careful and clear here. We often treat the Spirit as a substitute or surrogate for Jesus, as though the Spirit indwelling us is what Christ was promising when he said he would be with us. I think that's a mistake, a confusion of the persons of the Trinity. The Son is not the Spirit; the Spirit is not the Son.
So, "[our communion with Christ] is not simply with Christ in his divine nature separately taken, or with the Holy Ghost as the representative of his presence in the world..." (John Williamson Nevin, The Mystical Presence).
How then is Christ personally present with us? He is present through the Spirit. The key is the preposition through (or by in that original quote by Jason Stellman). The Spirit bridges the gap between us here on earth and Christ in heaven, making Christ in his person present with us. Horton writes, "The Spirit is the mediator of, not the surrogate for, Christ's person and work" (The Christian Faith: A Systematic Theology for Pilgrims on the Way). Robert Reymond, speaking more specifically of our union with Christ, speaks of the Spirit acting almost like an umbilical cord, connecting saints on earth to the Son in heaven (A New Systematic Theology Of The Christian Faith 2nd Edition - Revised And Updated). I think there is something to that. Christ is with us, especially made present in the sacraments and the word. At the same time, we are with Christ (Eph 2:4-6; see also Col 3:1-4). How can I, as a finite man be here and in heaven with Christ? How can Christ, also finite in his humanity, be here and in heaven? Through the power of the Holy Spirit.
Miraculous, mysterious, glorious.