By evidence gathered from Scripture the unity of Father and Son is proved, and firstly, a passage, taken from the Book of Isaiah, is compared with others and expounded in such sort as to show that in the Son there is no diversity from the Father's nature, save only as regards the flesh; whence it follows that the Godhead of both Persons is One. This conclusion is confirmed by the authority of Baruch.
20. Now the oracles of the prophets bear witness what close unity holy Scripture declares to subsist between the Father and the Son as regards their Godhead. For thus saith the Lord of Sabaoth: |Egypt hath laboured, and the commerce of the Ethiopians and Sabeans: mighty men shall come over to thee, and shall be thy servants, and in thy train shall they follow, bound in fetters, and they shall fall down before thee, and to thee shall they make supplication: for God is in thee, and there is no God beside thee. For thou art God, and we knew it not, O God of Israel.|
21. Hear the voice of the prophet: |In Thee,| he saith, |is God, and there is no God beside Thee.| How agreeth this with the Arians' teaching? They must deny either the Father's or the Son's Divinity, unless they believe, once for all, unity of the same Divinity.
22. |In Thee,| saith he, |is God| -- forasmuch as the Father is in the Son. For it is written, |The Father, Who abideth in Me, Himself speaketh,| and |The works that I do, He Himself also doeth.| And yet again we read that the Son is in the Father, saying, |I am in the Father, and the Father in Me.| Let the Arians, if they can, make away with this kinship in nature and unity in work.
23. There is, therefore, God in God, but not two Gods; for it is written that there is one God, and there is Lord in Lord, but not two Lords, forasmuch as it is likewise written: |Serve not two lords.| And the Law saith: |Hear, O Israel! The Lord thy God is one God;| moreover, in the same Testament it is written: |The Lord rained from the Lord.| The Lord, it is said, sent rain |from the Lord.| So also you may read in Genesis: |And God said, -- and God made,| and, lower down, |And God made man in the image of God;| yet it was not two gods, but one God, that made [man]. In the one place, then, as in the other, the unity of operation and of name is maintained. For surely, when we read |God of God,| we do not speak of two Gods.
24. Again, you may read in the forty-fourth psalm how the prophet not only calls the Father |God| but also proclaims the Son as God, saying: |Thy throne, O God, is for ever and ever.| And further on: |God, even thy God, hath anointed thee with the oil of gladness above thy fellows.| This God Who anoints, and God Who in the flesh is anointed, is the Son of God. For what fellows in His anointing hath Christ, except such as are in the flesh? You see, then, that God is by God anointed, but being anointed in taking upon Him the nature of mankind, He is proclaimed the Son of God; yet is the principle of the Law not broken.
25. So again, when you read, |The Lord rained from the Lord,| acknowledge the unity of Godhead, for unity in operation doth not allow of more than one individual God, even as the Lord Himself has shown, saying: |Believe Me, that I am in the Father, and the Father in Me: or believe Me for the very works' sake.| Here, too, we see that unity of Godhead is signified by unity in operation.
26. The Apostle, careful to prove that there is one Godhead of both Father and Son, and one Lordship, lest we should run into any error, whether of heathen or of Jewish ungodliness, showed us the rule we ought to follow, saying: |One God, the Father, from Whom are all things, and we in Him, and one Lord, Jesus Christ, by Whom are all things, and we by Him.| For just as, in calling Jesus Christ |Lord,| he did not deny that the Father was Lord, even so, in saying, |One God, the Father,| he did not deny true Godhead to the Son, and thus he taught, not that there was more than one God, but that the source of power was one, forasmuch as Godhead consists in Lordship, and Lordship in Godhead, as it is written: |Be ye sure that the Lord, He is God. It is He that hath made us, and not we ourselves.|
27. |In thee,| therefore, |is God,| by unity of nature, and |there is no God beside Thee,| by reason of personal possession of the Substance, without any reserve or difference.
28. Again, Scripture speaks, in the Book of Jeremiah, of One God, and yet acknowledges both Father and Son. Thus we read: |He is our God, and in comparison with Him none other shall be accounted of. He hath discovered all the way of teaching, and given it to Jacob, His servant, and to Israel, His beloved. After these things He appeared upon earth, and conversed with men.|
29. The prophet speaks of the Son, for it was the Son Himself Who conversed with men, and this is what he says: |He is our God, and in comparison with Him none other shall be accounted of.| Why do we call Him in question, of Whom so great a prophet saith that no other can be compared with Him? What comparison of another can be made, when the Godhead is One? This was the confession of a people set in the midst of dangers; reverencing religion, and therefore unskilled in strife of argument.
30. Come, Holy Spirit, and help Thy prophets, in whom Thou art wont to dwell, in whom we believe. Shall we believe the wise of this world, if we believe not the prophets? But where is the wise man, where is the scribe? When our peasant planted figs, he found that whereof the philosopher knew nothing, for God hath chosen the foolish things of this world to confound the strong. Are we to believe the Jews? for God was once known in Jewry. Nay, but they deny that very thing, which is the foundation of our belief, seeing that they know not the Father, who have denied the Son.