Isaiah 45:13

[The Septuagint reads], "You are God, and we knew it not." The words "we knew it not," spoken in the person of those of old who did not know him, occur only in the Septuagint. The Hebrew is different and is rendered by Aquila, "God then is strong and hidden, God that saves Israel," and by Theodotion, "Therefore a strong secret God preserves Israel." It is remarkable how [Isaiah] calls Christ a hidden God and gives the reason clearly as to why he calls him God alone among the ones begotten after the First and Unbegotten, namely, the dwelling of the Father in him.…According to this, then, the true and only God must be One and alone owning the name in full right. The Second, by sharing in the being of the true God, is thought worthy to share his name, not being God in himself or existing apart from the Father, but altogether being, living and existing as God, through the presence of the Father in him. [He is] one in being with the Father, and constituted God from him and through him, holding his being as well as his divinity not from himself but from the Father.

For taking into his hands the book of Isaiah he found as he read the section which contained the prophecy concerning himself; since Isaiah says in that section: Thus saith the Lord to his Anointed, to Cyrus, whose right hand I have holden to subdue nations before him, and I will loose the loins of kings. I will open the doors before him, and the gates shall not be shut. I will go before thee and will level mountains. I will break in pieces the doors of brass, and cut in sunder the bars of iron; and I will give thee the treasures of darkness, and hidden riches of secret places will I present to thee, that thou mayest know I am the Lord, which call thee by thy name, even the God of Israel. For Jacob my servant's sake and Israel my chosen, I have called thee by thy name and I will accept thee; and shortly afterwards: I have raised him up a king in righteousness, and I will make straight all his ways. He shall build my city, and lead back the captivity of my people, not for price nor reward, saith the Lord of hosts. Cyrus, struck with wonder at the foreknowledge and the prediction, and finding his own name expressly announced by the Prophet beforehand, ordered the people to go up to Jerusalem, after having released them from captivity, and given them funds wherewith to build their city and their temple. And not only did he do this, but those also who came after him did the same until the City and the Temple were finished