In reality and by nature it is the God of all, and His only-begotten Son and the Holy Spirit which are God. This is distinctly taught us by the admirable Paul in the words “For though there be that are called gods whether in heaven or in earth, as there are gods many and lords many, but to us there is but one God, the Father, of whom are all things, and we in Him; and one Lord by whom are all things and we by Him.” And the Holy Spirit is called the Spirit of God and so also is the soul of man, for, it is written, “His breath goes forth,” and “O you spirits and souls of the righteous bless ye the Lord,” and the Psalmist David called the angels spirits. “Who makes His angels spirits and His ministers a flame of fire.” Why indeed do I mention the angels and the souls of men? Even the dæmons are so called by the Lord “He shall take unto him seven other spirits more wicked than himself and they shall enter in, and the last state of that man shall be worse than the first.” But even this application of the name does not offend the pious reader, for the Father and His only begotten Son and His Holy Spirit are one God by nature; and the divine Word made man, our Lord Jesus Christ, is by nature one Son, only begotten of the Father; and the Comforter who completes the number of the Trinity is one Holy Ghost. Thus though many are named fathers, we worship one Father, the Father before the ages, who Himself gave this title to men, as the Apostle says, “For this cause I bow my knees unto the Father of our Lord Jesus Christ, of whom every fatherhood in heaven and earth is named.” Let us not then, because others are called christs, rob ourselves of the worship of our Lord Jesus Christ. For just as though many are called gods and fathers, there is one God and Father over all and before the ages; and though many are called sons, there is one real and natural Son; and though many are styled spirits there is one Holy Ghost; just so though many are called christs there is one Lord Jesus Christ by Whom are all things. And very properly does the Church cling to this name; for she has heard Paul, escorter of the Bride, exclaiming “I have espoused you to one husband that I may present you as a chaste virgin to Christ,” and again “Husbands love your wives as Christ also loved the Church,” and again “For this cause shall a man leave his father and mother, and shall be joined unto his wife, and they two shall be one flesh. This is a great mystery; but I speak concerning Christ and the Church.” Listen to him as he says “Christ has redeemed us from the curse of the law, being made a curse for us,” and elsewhere “Do you not know that so many of us as were baptized unto Jesus Christ were baptized into His death,” and in another place, “For as many of you as have been baptized into Christ have put on Christ,” and again “Put on the Lord Jesus Christ, and make not provision for the flesh, to fulfil the lust thereof.”
They who are blessed by the boons of God and have learned to know these passages and others like them, kindled with warm love for their bountiful Master, constantly carry on their lips this His dearest name and cry in the words of the Song of Songs “My beloved is mine and I am his;” “I sat down under his shadow with great delight, and his fruit was sweet to my taste.” And besides all this that name of ours which we love so well we have derived from the name of Christ. We are called Christians.
Of this name the Lord of all says, “The Lord God shall call His servants by another name which shall be blessed on the earth” and the following is the reason why the Church specially clings to this name. When the only-begotten Son of God was made man, then He was named Christ, then human nature received the beams of intellectual light; then the heralds of the truth shed their beams upon the world. Teachers of the Church, however, constantly used the names of the only begotten without distinction; at one time they glorify the Father the Son and the Holy Ghost; at another the Father with Christ and the Holy Ghost; yet as far as the sense is concerned there is here no difference. Wherefore after the Lord had commanded to baptize in the name of the Father and of the Son and of the Holy Ghost the blessed Peter said to them who received his preaching and asked what they must do, “Believe and be baptized every one of you in the name of our Lord Jesus Christ,” as though this name contained in itself all the potency of the divine command. The same teaching is clearly given us by the great Basil, luminary of the Cappadocians, or rather of the world. His words are “the name of Christ is the confession of the whole.” It indicates at once the Father, who anointed, the Son, who was anointed, and the Holy Ghost whereby He was anointed. Furthermore the thrice blessed Fathers assembled in council at Nicæa, after saying that we must believe in one God, the Father, added “and in one Lord Jesus Christ, the only begotten Son of God.” Thereby they teach that the Lord Jesus Christ is Himself the only begotten Son of God.
To what has been said it must also be added that we must not affirm that after the ascension the Lord Christ is not Christ but only begotten Son. The divine Gospels and the history of the Acts and the Epistles of the Apostle himself were, as we know, written after the ascension. It is after the ascension that the divine Paul exclaims “Seeing then that we have a great High Priest that is passed into the heavens, Jesus the Son of God, let us hold fast our profession.” And again, “For Christ is not entered into the holy places made with hands, which are the figures of the true; but into Heaven itself, now to appear in the presence of God for us.” And again after speaking of our hope in God he adds “which hope we have as an anchor both sure and steadfast, and which enters into that within the veil; whither the forerunner is for us entered, even Jesus made an High Priest for ever after the order of Melchisedec.” And when, writing to the blessed Titus about the second advent he says, “Looking for that blessed hope, and the glorious appearing of the great God and our Saviour Jesus Christ.” And to the Thessalonians he wrote in similar terms “For they themselves show of us what manner of entering in we had unto you, and how we turned to God from idols to serve the living and true God; and to wait for His Son from heaven, whom He raised from the dead, even Jesus, which delivered us from the wrath to come.” And again “And the Lord make you to increase and abound in love one toward another, and toward all men, even as we do toward you: to the end he may establish your hearts unblamable in holiness before God, even our Father, at the coming of our Lord Jesus Christ with all his saints.” And again when writing to the same a second time he says, “Now we beseech you, brethren, by the coming of our Lord Jesus Christ, and by our gathering together unto him.” And a little further on when predicting the destruction of antichrist he adds, “Whom the Lord shall consume with the spirit of his mouth, and shall destroy with the brightness of his coming.” And when exhorting the Romans to concord he says, “But why do you judge your brother? Or why do you set at naught your brother? For we shall all stand before the judgment seat of Christ. For it is written, as I live, says the Lord, every knee shall bow to me, and every tongue shall confess to God.” And the Lord Himself when announcing His second advent besides other things says too this “Then if any man shall say unto you, Lo, here is Christ, or there; believe it not. For as the lightning comes out of the east, and shines even unto the west, so shall also the coming of the Son of Man be.”
Source: Letters (New Advent)