What is Christ the God-Man? What in Him is God and what man? How is God known in the God-Man, and how is man? What has God given to us men in and and with the God-Man? The Holy Spirit, the Spirit of Truth, tells us all the truth there is about Him, about God in Him and man in Him and all that is given us through Him. All this immeasurably transcends everything that the human eye has ever seen, the ear has ever heard, or has ever entered into the heart of man (I Cor. 2:9; cf. Jn 15:26; 16:13; I Cor. 2:4; Eph. 3:5).
Through His life in the flesh on earth, the God-Man founded His theanthropic Body, the Church, and in this way prepared the earthly world for the Holy Spirit’s coming into the world, and His life and activity in the Body of the Church as the Soul of that Body. On the holy Day of Pentecost, the Holy Spirit descended from heaven into the theanthropic Body of the Church and remains eternally in it as its life-giving Soul (Acts 2:1-47). This visible theanthropic Body of the Church was constituted by the holy apostles with their holy faith in the Theanthropos, the Lord Jesus, as the Savior of the world, as perfect God and perfect Man. The descent and activity of the Holy Spirit in the theanthropic Body of the Church is because of, and for the sake of, the Theanthropos (cf. Jn 16:7-13; 15:26; 14:26). “For His sake the Holy Spirit entered into the world.”  Everything in the dispensation of salvation is brought about by the theanthropic Person of the Lord Christ, and everything comes about in the framework of theanthropy. This is also the case with the activity of the Holy Spirit. All His activity is of one essence with the theanthropic ascesis of the salvation of the world by the Lord Christ. Pentecost is, with all the immortal gifts of the Triune Godhead, of the Holy Spirit Himself, intended for the holy apostles; the holy apostolic Faith and Tradition, the hierarchy and everything that is apostolic and theanthropic.
The Day of the Holy Spirit, which began on the Day of Pentecost, is ever present in the Church in the inexpressible fullness of all the divine gifts and the life-giving powers (Acts 10:44-48; 11:15-16; 15:8-9; 19:6). Everything in the Church comes about through the Holy Spirit, from the least to the greatest. When the priest blesses the censer before censing, he prays to the Lord Christ to “send down the grace of the Holy Spirit.” The clearest testimony that the entire life of the Church comes from the Holy Spirit is at the consecration of a bishop, when God’s indescribable miracle, holy Pentecost, is repeated and the fullness of grace is given. There is no doubt that the Lord Christ is in the Church through the Holy Spirit, and that the Church is in the Lord Christ through the Holy Spirit. The Lord Christ is the Head and Body of the Church; the Holy Spirit is its Soul (cf. I Cor. 12:1-28). From the very beginning of the theanthropic dispensation of salvation, the Holy Spirit has made Himself a part of the foundation of the Church, the foundation of the Body of Christ, by “bringing about the incarnation of the Logos in the Virgin.” 
In fact, every holy mystery and holy virtue is a little Pentecost; in them, the Holy Spirit descends upon us, into us. He descends in His essence,  He, “the richness of the Godhead,” “the grace of the open seas,”  “from Him come grace and life for every creature.” 
The Lord dwells in us by the Holy Spirit, and we in Him. This is testified to us by the presence of the Holy Spirit in us. We live by the Holy Spirit in Christ, and He in us. We know this “by the Spirit which He hath given us” (I Jn. 3:24). Through the Holy Spirit, our human spirit is brought to a true and a right knowledge of Christ. That which is in God, and in the God-Man, we know by the Holy Spirit that “He hath given us” (cf. I Jn 4:13; I Cor. 2:4-16).
To come to the knowledge of Christ the Theanthropos, one of the Holy and Divine Trinity, we need the help of the other Holy Two: God the Father and God the Holy Spirit (cf. Matt. 11:27, I Cor. 2:12). The Holy Spirit is “the Spirit of wisdom” (Eph. 1:17); if we receive Him, we are filled with the wisdom of God. The Holy Spirit is also “the Spirit of revelation” (Eph. 1:17). By God’s wisdom, He reveals and proclaims the mystery of Jesus the Theanthropos in the heart of the believer, and thus the spirit-bearer acquires real knowledge of Christ. No human spirit can, by any imaginable effort, comprehend the mystery of Christ in its divine and saving perfection and completeness. This is revealed to the human spirit only by the Holy Spirit, and this is why He is referred to as “the Spirit of revelation” (Eph. 1:17; 3:6; I Cor. 2:10). The Apostle, enlightened by the Holy Spirit, therefore proclaims: “No man can say that Jesus is the Lord, but by the Holy Spirit” (I Cor. 12:3). The Holy Spirit, “the spirit of truth” and “the Spirit of revelation,” leads us into all the truth of Christ’s Person and His theanthropic dispensation of salvation, and teaches us all that is Christ’s (Jn. 16:13 14:26; I Cor 2:6-16). This is the reason why the entire Gospel of Christ, with all its theanthropic realities, is called the Revelation. This is the reason why every office, labor, service, sacrament and act in church in performed with the invocation of the power and grace of the Holy Spirit.
The entire life of the Church, in its innumerable theanthropic realities and aspects, is led and guided by the Holy Spirit, who is ever the Spirit of Jesus Christ, the Theanthropos. This is why it is said in Holy Scripture: “If any man have not the Spirit of Christ, he is none of His” (Rom. 8:9). Saint Basil, angelically immersed in the theanthropic mystery of the Church as the loveliest and greatest of God’s mysteries, proclaims the truest good tidings: “The Holy Spirit builds up the Church of God.” 
 Prayer at the end of the Akathist to the Most Sweet Jesus.
 The Octoechos, Tone I, on Sundays at the Midnight Office: Canon to the Holy Trinity, Ode 1, Theotokion.
 The Pentecostarion, in the Aposticha at Matins on Pentecost Tuesday.
 idem, on the Tuesday after Pentecost, the Three-Canticled Canon, Canticle 9; also on Friday of the same week, Canticle 8 (in the Slavonic Pentecostarion).
 The Octoechos, Tone 3, on Sunday morning, Hymn of Degrees, Antiphon 3.
 St Basil the Great: In Isai., III; PG 30: 289D