In creation, we are united to the Life of God the Father. By the Incarnation of the Word, the Son of God, we became, as St. Peter declares, "partakers of the Divine nature." Humanity became united to the Life of God the Son through Jesus Christ; and now the Life of God the Holy Ghost, the Spirit of Love, descends and fills with Divine grace the hearts of the faithful children begotten to God through the creation and Incarnation; the union between God and man is complete, and the love of God to man is exhausted.
Truly, the Father Almighty was a Comforter, to bring us out of nothingness, and bestow upon us the boon of being and the joys of an eternal existence. God the Son was a Comforter in redeeming us, and regenerating us, and giving us the right, which angels might envy, to call our Creator our Father; but the Holy Ghost was yet another Comforter, and He would not deny Himself to those whom the Father had loved to create, whom He had yet loved more so as to send His only-begotten Son, that whosoever believeth in Him "might have life, and might have it more abundantly"; and thus the life of man becomes exalted and deified by its union with the Eternal, Infinite life of the Triune God.
Look down from the deck of a ship in mid-ocean, and pierce the mighty depths of waters with a glance. Look up into the blue vault of heaven, and with unaided vision scan the uttermost bounds of space, far beyond the dizzy distances where roll the last stars in their lonely course; but fathom if you can the height, the depth, the immensity of that Infinite Life of the Father, the Son, and the Holy Ghost, in which, as in a boundless and fathomless ocean of comfort, and as in a measureless firmament of glory and of rapture, the soul of man is swallowed up and lost in the love of his God.
But who among men belong thus entirely to God? To whom does the Holy Ghost come in His fulness? Not to all; for I read that our Lord said that "the world cannot receive Him, because it seeth Him not, nor knoweth Him." [Footnote 29] To whom, then? Let St. John answer us: "As many as received Him (Jesus Christ, who is the Word of God), to them He gave power to become the sons of God, to them who believe in His name. Who are born, not of blood, nor of the will of the flesh, nor of the will of man, but of God." [Footnote 30]
[Footnote 29: St. John xiv. 17.]
[Footnote 30: Ibid. i. 12, 13.]
It is not enough, then, to be a creature of God, to be born of the flesh, or of the will of man. The soul who would receive the Holy Ghost, to see and have God in His fulness, must be born of God. "Except a man be born of water and the Holy Ghost, he cannot enter into the kingdom of God." [Footnote 31] As the Son of God became incarnate by the Holy Ghost of the Virgin, so the sons of men must be born again of water and the Holy Ghost in Baptism, to become the sons of God. Then, and then only, can we call God Father. Then, and then only, do we "receive the spirit of adoption of sons," as St. Paul declares, "whereby we cry, Abba (Father)." [Footnote 32] We must believe in the Word made flesh, in Jesus Christ, else that other Comforter will not come unto us; and hence the Church invokes the Holy Ghost to come down into the hearts of the faithful, or the believers in Jesus Christ.
[Footnote 31: Ibid. iii. 5.]
[Footnote 32: Rom. viii. 15.]