I was delighted to find this quote via the Orthodox Study Bible, though I must add to my complaints about that edition the fact that they cite church fathers by name, but without providing a reference to the particular work. A visit to the St. Pachomius Library and then ewtn.com resolved the latter question.
The quote is from St. Gregory the Theologian’s Second Paschal Oration, XXII:
TWENTY-TWO Now we are to examine another fact and dogma, neglected by most people, but in my judgment well worth enquiring into. To Whom was that Blood offered that was shed for us, and why was it shed? I mean the precious and famous Blood of our God and Highpriest and Sacrifice. We were detained in bondage by the Evil One, sold under sin, and receiving pleasure in exchange for wickedness. Now, since a ransom belongs only to him who holds in bondage, I ask to whom was this offered, and for what cause? If to the Evil One, fie upon the outrage! If the robber receives ransom, not only from God, but a ransom which consists of God Himself, and has such an illustrious payment for his tyranny, a payment for whose sake it would have been right for him to have left us alone altogether. But if to the Father, I ask first, how? For it was not by Him that we were being oppressed; and next, On what principle did the Blood of His Only begotten Son delight the Father, Who would not receive even Isaac, when he was being offered by his Father, but changed the sacrifice, putting a ram in the place of the human victim? Is it not evident that the Father accepts Him, but neither asked for Him nor demanded Him; but on account of the Incarnation, and because Humanity must be sanctified by the Humanity of God, that He might deliver us Himself, and overcome the tyrant, and draw us to Himself by the mediation of His Son, Who also arranged this to the honour of the Father, Whom it is manifest that He obeys in all things? So much we have said of Christ; the greater part of what we might say shall be reverenced with silence. But that brazen serpent [Num. 21:9] was hung up as a remedy for the biting serpents, not as a type of Him that suffered for us, but as a contrast; and it saved those that looked upon it, not because they believed it to live, but because it was killed, and killed with it the powers that were subject to it, being destroyed as it deserved. And what is the fitting epitaph for it from us? "O death, where is thy sting? O grave, where is thy victory?" Thou art overthrown by the Cross; thou art slain by Him who is the Giver of life; thou art without breath, dead, without motion, even though thou keepest the form of a serpent lifted up on high on a pole.
There are two elements that particularly attracted me to this quote. The OrthSB quotes the final section about the serpent, which goes well with this week’s lectionary texts. I like the idea that it was precisely the fact that the serpent on the pole is dead that provides the healing. He is a defeated serpent. It would also provide some interesting context to the worship of the serpent up to Hezekiah’s time, that is until Hezekiah broke it up (2 Kings 18:4). This differs from part of the interpretation I provided yesterday in my Numbers 21:4-9" href="index.php?option=com_content&view=article&id=69&catid=2&Itemid=5" target="_blank">lectionary notes.
If you’re missing out on the eastern church fathers regarding the atonement, you are missing out on a lot.