Hi Liturgist! You do know, I would think, that the RCC also rejects that particular nugget of Augustine’s teachings?
Not sufficiently, which is why your church felt the need to develop the doctrine of the Immaculate Conception, which would be superfluous from an Orthodox perspective, since it is not the process of conception that causes one to inherit the sinful condition. We are conceived in sin, but are not corrupted by original sin as a result of our conception, but rather because the condition of hereditary sin applies in general and would be unavoidable.
Furthermore, the idea that all conceptions except for that of the Theotokos are unclean contradicts the Scriptural statement that the marriage bed is undefiled. Conception, whether due to concupiscence or some other aspect of human reproduction, is not the means by which we inherit original sin.
Thus the Orthodox believe the Theotokos was conceived in the same way as everyone else, which furthermore protects the full humanity of Jesus Christ - she also required salvation from her Son, just like everyone else, despite not, according to our faith, ever having committed an intentional act of sin (or having sinned through negligence or omission), but rather, she was saved by her Son, because of original sin.
Indeed, that she was taken up to heaven bodily at the Dormition (called the Assumption by the Oriental Orthodox) and there revived after her death (which she would not have experienced had she not been born into original sin) contradicts the Immaculate Conception.
The problem with the Immaculate Conception dogma is that it has caused some Catholics to deny that the Theotokos died at the incarnation (and the dogmatic definition of Pope Pius XII on the issue did not bring clarity to the issue, but rather seems to have been written to accomodate both views), and this in turn has led to groups like the Fifth Dogma people who advocate for the Theotokos to be declared “Co-Redemptrix” which would be an extreme and intolerable soteriological, Mariological, Christological and eschatological error (fortunately, they are a minority, and their case is not helped by the fact that it is connected to the spurious apparitions seen by Ida Peerdeman, which were deemed by the CDF to be unworthy of belief, in which Ida Peerdeman was visited by “The Lady who was once Mary”, a title used by no apparition of the Theotokos regarded as genuine by the CDF, and who behaved in a threatening manner which is behavior unrecorded in the Bible and accepted Hagiopgraphic material and hymnody of the ancient church, and can thus be regarded as behavior not expected from Our Glorious Lady Theotokos and Ever Virgin Mary, who lovingly points us to her Son our God and Savior, Jesus Christ, and therefore despite some efforts at promoting it by a recent Archbishop of Amsterdam in a dangerous attempt to promote his local church without considering adverse theological implications, is not widely accepted), however, all of this aside, it is worth nothing that there would be no “Fifth Dogma” initiative if it had not been for the Immaculate Conception, which in turn would not have been an issue had it not been for Vatican I and Papal Infallibility.
I would also note that insofar as it apparently took a dogmatic definition from Pope Pius XII to make the Assumption official dogma of the Roman Catholic Church, the RCC does not appear to follow the principle of Lex Orandi, Lex Credendi, considering that the Assumption had been celebrated liturgically since antiquity and was regarded as dogma in the Orthodox church since antiquity.
Nothing celebrated in the liturgy of the Eastern Orthodox or Oriental Orthodox churches lacks dogmatic or doctrinal standing - indeed, those parts of scripture read liturgically are regarded as more important than those which aren’t, and the more frequently something is read, or the more prominent its use, the more important it is (thus the seven Resurrection Gospels read at Matins, the Beatitudes, and certain Psalms such as 102, 103, 106, 94, and 95 (LXX) are among the most important liturgical texts for us, and John 1:1-14, which is read at the end of the Divine Liturgy in the Armenian Apostolic Church, is one of the most important liturgical texts for them (this was a Latinization, but a good one; I think one of the worst changes in the Novus Ordo Missae was deleting the Last Gospel, and I strongly advocate for its use in all Western Rite churches during all Solemn Masses with a deacon; likewise most of the Western Rite Orthodox use it).
Furthermore, while the Roman Catholic Church heavily edited the liturgies of the Sui Juris churches that were set up to compete with the Oriental Orthodox and the Church of the East such as the Coptic Catholics, Syriac Catholics, Chaldean Catholics, Syro-Malabar Catholics, Malankara Catholics and Ethiopian Catholics under the assumption, later shown to be inaccurate by Pope Benedict XVI during his tenure, that those churches were heretical, in the case of the Greek Catholics, the Byzantine Rite Catholics, while some Latinization did occur, it was less severe and less pervasive than in most other Eastern Catholic churches. This has led to some contradictions - for example, the Eastern Catholics celebrate the second Sunday of Lent as the Sunday of St. Gregory Palamas, who is not venerated in the Western church and who taught things which contradicted Thomas Aquinas. Additionally most Eastern Catholic Churches do not use the filioque, although this is less of a contradiction than it might seem - Rome did declare that the filioque would be misleading if expressed in Greek, and while the vast majority of Greek Catholics are not Greek (indeed the Byzantine Catholic Church in Greece has just four parishes and 6,000 members and is smaller than even the Russian Greek Catholic Church (which has 13 parishes in Russia in addition to some abroad, for example, there is one in Los Angeles), it seems reasonable that since so much Greek theology is preserved in the Greek Catholic / Byzantine Rite churches, that to introduce the filioque would cause confusion therein.
