==The idea of millions of years comes from the Catholic Church, from Origen of Alexandria (185-254 AD)
Wrong:
Origen: ‘After these statements, Celsus, from a secret desire to cast discredit upon the Mosaic account of the creation, which teaches that the world is not yet ten thousand years old, but very much under that, while concealing his wish, intimates his agreement with those who hold that the world is uncreated. For, maintaining that there have been, from all eternity, many conflagrations and many deluges, and that the flood which lately took place in the time of Deucalion is comparatively modern, he clearly demonstrates to those who are able to understand him, that, in his opinion, the world was uncreated. But let this assailant of the Christian faith tell us by what arguments he was compelled to accept the statement that there have been many conflagrations and many cataclysms, and that the flood which occurred in the time of Deucalion, and the conflagration in that of Phaethon, were more recent than any others.’ Contra Celsum (Against Celsus) 1.19, Ante-Nicene Fathers4:404.
In Contra Celsus in the passage you cited, Origen is arguing against Celsus' Biblical literalism, not the age of the earth. Celsus argument is that the OT is obviously false and that Christians ignore the meanings of the words to gloss over errors. Have you abandoned literalism?
In what follows, Celsus, assailing the Mosaic history, finds fault with those who give it a tropical and allegorical signification. And here one might say to this great man, who inscribed upon his own work the title of a True Discourse, "Why, good sir, do you make it a boast to have it recorded that the gods should engage in such adventures as are described by your learned poets and philosophers, and be guilty of abominable intrigues, and of engaging in wars against their own fathers, and of cutting off their secret parts, and should dare to commit and to suffer such enormities; while Moses, who gives no such accounts respecting God, nor even regarding the holy angels, and who relates deeds of far less atrocity regarding men (for in his writings no one ever ventured to commit such crimes as Kronos did against Uranus, or Zeus against his father, or that of the father of men and gods, who had intercourse with his own daughter), should be considered as having deceived those who were placed under his laws, and to have led them into error?"
Contra Celsus 1.17
I'll repeat my previous post since it's clear you didn't read it.
Combining the Stoic doctrine of a universe without beginning with the Biblical doctrine of the beginning and the end of the world, he(Origen) conceived of the visible world as the stages of an eternal cosmic process, affording also an explanation of the diversity of human fortunes, rewards, and punishments.