First let me thank you for the warm reception you have given my pieces. I have been, and am, working on this subject, and the notes I have posted were, initially, just for my own use. That gave me two sorts of hesitation: were they actually coherent; and was it a little egotistical of me to think that they would be of interest to others? But then, in the 'conversion' thread, the subject came up, which gave me the courage to post ... and see!
For the Coptic Church it is something of a hot potato because of some trying to read into the doctrine the idea that we actually 'become gods' and partake of the divine essence; we can see as early as Irenaeus that such a notion is ruled out because we have no ontological connection with God. Indeed, as I hope the piece on Origen will show (it needs a little more work before I post it), the idea is at the root of the soteriology he develops and which is, in many ways, perfected by St. Cyril. I am painfully conscious that beyond that point, what little expertise I have runs dry, and am busy reading both St. John Damascene and St. Maximus (although too little of the latter is available in English or French or German, which are the only languages I have) who clearly have interesting things to say; but how much they add to what St. Cyril wrote is the real question I am asking myself. If anyone has an answer, I'd really appreciate it
Your post adds substance to any discussion. The threefold process you describe is certainly a later development, and does seem to be part of the contribution made by St. Maximus. Certainly for Origen, the process is still recognisably the same as it was for St. Clement, but he edges us towards a subtler and more articulated way of thinking about theosis as a process. But I am constantly reminded of my limitations here, and if there is anyone out there reading this who can offer a better insight, I'd welcome the contribution; again, I stress that these pieces originated as notes for my own use.
On the pedagogy front, I am with you. I know that Peter and Abba Seraphim have wanted us to do more here, and, as a professional teacher, I feel my own frustration at not having more time to help us produce some catechetical works. +Kallistos' famous book is excellent, of course, but from the Oriental Orthodox perspective, leaves something to be desired.
But I am also conscious of the perpetual catechesis that our clergy perform in their homilies. I am, of course, very fortunate in that I get to hear Abba Seraphim every other Sunday, and a collection of his homilies (now there's a good idea) would amount to quite an education in Orthodoxy. But I know that other clergy also talk to us about theosis. Indeed, I know of one (whom I will not embarrass by naming) who dwells on this theme consistently, using the hospital analogy - and emphasising that however good the care, if the patient carries on abusing his or her body, it will avail naught.
Indeed, not only is this a favourite theme of that priest, he emphasises, to himself and his flock, that part of his work with us is to know which spiritual medicine to prescribe to which person; so theosis requires us to work with a skilled physician, so to say; this is not just (or even) Do It Yourself medicine; though it certainly isn't 'someone else do it for you' medicine either.
And here, we come back to the idea of the Church as a family. I am struck, constantly, by something we so take for granted that we don't always, I suspect, grasp its significance - and that is the use of metaphors about family. God is 'the Father', Christ is 'the Son' and we can become 'sons of God' by 'adoption', and we are His 'children'. It may be that in the Western nucleated family we miss the richness of the extended family structures of the Middle East. But the 'abba' of the Lord' Prayer is not a stern and vengeful 'father', who is distant from us, He is a 'daddy' who loves us and who wants the best for us - and He has also provided a way for us to follow - and a person who has, in His own life, shown us that way.
Your post offers us a number of good questions to deal with - for which I am grateful as I press on with Origen; trying to compress what he writes is a real exercise - and a privilege.
Again, I am grateful for your engagement and encouragement.
In this is love, not that we loved God, but that He loved us and sent His Son to be the propitiation for our sins. (1 John 4:10)