Know when Eastern Orthodox stopped teaching Transubstantiation? If that is what was believed & taught by all of the Early Church Fathers as you claim, Easthern Orthodox churches would also be teaching it, but they don’t.
“The body which is born of the holy Virgin is in truth body united with divinity, not that the body which was received up into the heavens descends, but that the bread itself and the wine are changed into God’s body and blood. But if you enquire how this happens, it is enough for you to learn that it was through the Holy Spirit, just as the Lord took on Himself flesh that subsisted in Him and was born of the holy Mother of God through the Spirit. And we know nothing further save that the Word of God is true and energises and is omnipotent, but the manner of this cannot be searched out. But one can put it well thus, that just as in nature the bread by the eating and the wine and the water by the drinking are changed into the body and blood of the eater and drinker, and do not become a different body from the former one, so the bread of the table and the wine and water are supernaturally changed by the invocation and presence of the Holy Spirit into the body and blood of Christ, and are not two but one and the same.” John of Damascus, Exposition of the Orthodox Faith, 4:13 (A.D. 743).
Good Night,Dear Friend,I,m tired
COUNCIL OF CONSTANTINOPLE (1727)
In an article concerning the Eucharist in an exposition of faith by a council held at Constantinople in 1727 we find a re-affirmation that the word “TRANSUBSTANTIATION” is “the most fitting statement of this mystery” and the “most accurately significant declaration of this change” in the elements. This Council reads —
“It is right to believe and confess that the most mystic and all-holy rite and Eucharist of the holy Liturgy and BLOODLESS SACRIFICE, which is for a memorial of Christ our God voluntarily sacrificed on our behalf, is celebrated in the following way. Leavened bread is offered and wine together with warm water is placed in the holy cup, and they are supernaturally changed, the bread into that life-giving body of the Lord and the wine into His precious blood, by the all-holy Spirit by means of the prayer and invocation of the priest which depends on the power of the words of the Lord.
“Not that the consecration is effected by the words ‘Take, eat,’ etc., or by the words ‘Drink ye all of it,’ etc., as the Latins think; for we have been taught that the consecration takes place at the prayer of the priest and at the words which he utters, namely, ‘Make this bread the precious body of Thy Christ, and that which is in this cup the precious blood of Thy Christ, changing them by Thy Holy Ghost,’ as the most glorious Apostles and Fathers filled with the Spirit who compiled the holy liturgies explained and handed down, and as this tradition of their divine teaching has come to us and to the Holy Church of Christ, and as also is clearly shown by the example of the Lord Himself, who first prayed and then commanded His Apostles, ‘Do this for My memorial.’
“Therefore we acknowledge that at the invocation of the priest that ineffable mystery is consecrated, and the living and with-God-united body itself of our Savior and His blood itself are really and substantially present, and that the whole without being in any way impaired is eaten by those who partake and is BLOODLESSLY SACRIFICED. And we believe without any doubt that in the reception and communion of this, even though it be in ONE KIND ONLY, the WHOLE AND COMPLETE CHRIST is present; nevertheless according to the ancient tradition which has prevailed in the Catholic Church we have received that Communion is made by all the faithful, both clergy and laity, individually in both kinds, and not the laity in one kind and the priests in both, as is done in the innovation which the Latins have wrongly made.
“As an explanatory and MOST ACCURATELY SIGNIFICANT DECLARATION OF THIS CHANGE of the bread and the wine into the body of the Lord itself and His blood the faithful ought to acknowledge and receive the word TRANSUBSTANTIATION, which the Catholic Church as a whole has used and receives as the MOST FITTING STATEMENT OF THIS MYSTERY. Moreover they ought to reject the use of unleavened bread as an innovation of late date, and to receive the holy rite in leavened bread, as had been the custom from the first in the Catholic Church of Christ.” (Stone, page 182-184)
What this Council shows us is the Eastern Orthodox had differences with the Latins (Catholics) during this period in practice (Communion under both kinds, leavened bread) and the exact moment of consecration, but had no difficulty in affirming the reality of the change by using the term TRANSUBSTANTIATION as the “MOST FITTING STATEMENT OF THIS MYSTERY” and “MOST ACCURATELY SIGNIFICANT DECLARATION OF THIS CHANGE.”
Q. 55. Which is the sixth article of faith?
R. “Who ascended into the heavens, and sits at the right hand of God the Father.” (44)
Q. 56. How many things does this article of faith teach?
R. This article teaches four things. First (sic), that he ascended into heaven in the same body, in which he suffered and resurrected from the dead, and sits at the right hand of the Father, in glory and praise. (45) Secondly, it teaches that he ascended into heaven only as man, since as God he always was in heaven and everywhere. Thirdly, it teaches that he never abandoned that humanity, which he once took from the Virgin Mary, and in which he will come again in judgment, just as the Angels announced to the Apostles: “This Jesus who is taken up from you into heaven, shall so come, as you have seen him going into heaven.”[140] Fourthly, it teaches that Christ is in heaven according to his humanity, but not on earth (46), the singular exception being the most holy Eucharist, wherein Christ himself is really present through transubstantiation of the substance of bread into the substance of his holy body and through the transubstantiation of the substance of wine into the substance of his most precious blood Wherefore should we revere the most holy Eucharist and adore it by the worship of latria, because such is due the Savior himself.
From the Orthodox Confession of Faith, Peter Mohila, Metropolitan of Kiev (1633-47)
http://www.esoptron.umd.edu/UGC/ocf1c.html