Malachi 2:10

Truly, then, the Scripture declared, which says, "First of all believe that there is one God, who has established all things, and completed them, and having caused that from what had no being, all things should come into existence:" He who contains all things, and is Himself contained by no one. Rightly also has Malachi said among the prophets: "Is it not one God who hath established us? Have we not all one Father?" In accordance with this, too, does the apostle say, "There is one God, the Father, who is above all, and in us all." Likewise does the Lord also say: "All things are delivered to Me by My Father;" manifestly by Him who made all things; for He did not deliver to Him the things of another, but His own. But in all things [it is implied that] nothing has been kept back [from Him], and for this reason the same person is the Judge of the living and the dead; "having the key of David: He shall Open, and no man shall shut: He shall shut, and no man shall open." For no one was able, either in heaven or in earth, or under the earth, to open the book of the Father, or to behold Him, with the exception of the Lamb who was slain, and who redeemed us with His own blood, receiving power over all things from the same God who made all things by the Word, and adorned them by [His] Wisdom, when "the Word was made flesh;" that even as the Word of God had the sovereignty in the heavens, so also might He have the sovereignty in earth, inasmuch as [He was] a righteous man, "who did no sin, neither was there found guile in His mouth;" and that He might have the pre-eminence over those things which are under the earth, He Himself being made "the first-begotten of the dead;" and that all things, as I have already said, might behold their King; and that the paternal light might meet with and rest upon the flesh of our Lord, and come to us from His resplendent flesh, and that thus ma […]

(Verse 10 and following) Is not the Father one of us all? Is not God one who created us? Why then does each one of us despise his brother, violating the covenant of our fathers? Judah has transgressed, and abomination has been made in Israel and in Jerusalem: because Judah has defiled the sanctification of the Lord, which he loved, and has taken the daughter of a foreign god. The Lord will destroy the man who does this, the master and the disciple from the tents of Jacob, and the one who offers an offering to the Lord of hosts. LXX: Is not the Father of you all one? Did not one God create you? Why have you each forsaken his brother, making the abominable testament of your fathers? Judas has been abandoned, and abomination has been made in Israel and in Jerusalem, because Judas defiled the holy things of the Lord, in which he loved, and he discovered foreign gods. May the Lord destroy the man who does these things, until he is driven out from the tents of Jacob, and from those who offer sacrifice to the Almighty Lord. Before we discuss the current chapter, the tradition of the Hebrews must be presented, indeed the truth of the Scriptures must be explained. We read in a volume titled Ezra, spoken in the person of Ezra himself: The leaders approached me, saying: The people of Israel, as well as the priests and Levites, have not separated themselves from the peoples of the lands and from their abominations, namely the Canaanites, Ethiopians, Persians, Jebusites, Ammonites, Moabites, Egyptians, and Amorites. For they have taken of their daughters for themselves, and for their sons: and the holy seed is mixed with the people of those lands. Moreover the hand of the princes and magistrates hath been first in this transgression. […]

But this is God's kindness to humanity, that of whom he is the maker, of them according to grace he afterwards becomes Father also. He becomes, that is, when people, his creatures, receive him into their hearts, as the apostle says, "the spirit of his Son, crying, 'Abba, Father.' " And these are they who, having received the word, gained power from him to become sons of God; for they could not become sons, being by nature creatures, otherwise than by receiving the spirit of the natural and true Son.

One father - Abraham, or Jacob, with whom God made the covenant by which their posterity were made a peculiar people. Created us - The prophet speaks of that great and gracious work of God, creating them to be a chosen people. And so we Christians are created in Christ Jesus.

And that which was at the bottom of this and other instances of profaneness and downright atheism, thinking God altogether such a one as themselves, which was, in effect, to say, There is no God,