Origen has long been a controversial figure in church history. The third century church father was student of Clement of Alexandria, and taught at the Catechetical School at Alexandria. For better or worse, Origen was highly influential on several generations following him, until he was eventual posthumously condemned as a heretic many centuries after he lived by an ecclesiastical council. Prior to this there had been protracted controversy about his orthodoxy for centuries, with many church fathers writing in opposition and in defense of him.
Without commenting further on Origen’s contributions to theology at large, it will serve our purposes simply to note that Origen stands amid a long line of early Christian theologians who taught that the one God of the Christians faith is not the Trinity, but the person of God the Father in particular. We see this belief expressed by Origen in the following quotes:
“The particular points clearly delivered in the teaching of the apostles are as follow:– First, That there is one God, who created and arranged all things, and who, when nothing existed, called all things into being–God from the first creation and foundation of the world–the God of all just men, of Adam, Abel, Seth, Enos, Enoch, Noe, Sere, Abraham, Isaac, Jacob, the twelve patriarchs, Moses, and the prophets; and that this God in the last days, as He had announced beforehand by His prophets, sent our Lord Jesus Christ to call in the first place Israel to Himself, and in the second place the Gentiles, after the unfaithfulness of the people of Israel. This just and good God, the Father of our Lord Jesus Christ, Himself gave the law and the prophets, and the Gospels, being also the God of the apostles and of the Old and New Testaments.” De Principiis, Preface 4.
“But whether Orpheus, Parmenides, Empedocles, or even Homer himself, and Hesiod, are the persons whom he means by “inspired poets,” let any one show how those who follow their guidance walk in a better way, or lead a more excellent life, than those who, being taught in the school of Jesus Christ, have rejected all images and statues, and even all Jewish superstition, that they may look upward through the Word of God to the one God, who is the Father of the Word.” Origen Against Celsus, Book VII. Chapter XLI.
“Accordingly, we worship with all our power the one God, and His only Son, the Word and the Image of God, by prayers and supplications; and we offer our petitions to the God of the universe through His only-begotten Son.” Origen Against Celsus, Book VIII. Chapter XIII.
This matches with the apostle Paul’s inspired confession in 1 Corinthians 8:6 “yet for us there is but one God, the Father, from whom are all things and we exist for Him; and one Lord, Jesus Christ, by whom are all things, and we exist through Him.” (NAS), as well as the later teaching of the Nicene Creed which begins by stating that “We believe in one God, the Father Almighty…”. For an extensive list of quotes from other church fathers on the same subject, see here: https://contramodalism.com/2017/03/08/i-believe-in-one-god-the-father-almighty/ .