It is my understanding that Ancestral Sin is the world that we are born into. A fallen and sinful world made possible by our first parents. Original Sin as the RCC teaches, is a guilt that is inherited by all humans which I do not ascribe to.
It is always necessary, whether one is Catholic or Orthodox, to ask whether popular teaching accurately reflects the authoritative dogmatic teaching of the Church.
I do not dispute that in the Catholic Church original sin has often been communicated, especially at the parochial level, as the imputation of Adam's original sin to subsequent generations (thus St Augustine); but following St Thomas Aquinas and the Council fo Trent, most Catholic theologians have understood original sin as the
privation of sanctifying grace. It is this privation that humanity inherits. In addition to reading the relevant sections of the Catholic Catechism, also see the
catechetical instruction of Pope John Paul II.
Now whether the Latin construal of the privation of sanctifying grace is acceptable to Orthodoxy is a separate question; but if it is not, then very different objections will need to be adduced. Popular Orthodox polemics simply miss the point. One Orthodox theologian who did see the point was Sergius Bulgakov (see his book
The Burning Bush: On the Orthodox Veneration of the Mother of God). Bulgakov rejects the IC dogma because he rejects what he sees to be an unwarranted separation of nature and supernature in the Tridentine formulation of grace and on this basis rejects the scholastic notion of sanctifying grace. This separation has itself been severely critiqued by modern Catholic theologians (e.g., Henri de Lubac, Karl Rahner, and Hans Urs von Balthasar).
As I have repeatedly argued on this forum, Orthodox polemicists need to stop accusing Catholics of being guilty of "original guilt." It's just irresponsible. See
this series of blog articles on original sin that I wrote several years ago when I was Catholic.
May I also suggest that the real question here is one with which both Latin and Eastern Christians have struggled, namely,
the salvific necessity of Holy Baptism. Thus we read in the Orthodox Confession of Dositheus:
We believe Holy Baptism, which was instituted by the Lord, and is conferred in the name of the Holy Trinity, to be of the highest necessity. For without it none is able to be saved, as the Lord says, "Whoever is not born of water and of the Spirit, shall in no way enter into the Kingdom of the Heavens." {John 3:5} And, therefore, baptism is necessary even for infants, since they also are subject to original sin, and without Baptism are not able to obtain its remission. Which the Lord showed when he said, not of some only, but simply and absolutely, "Whoever is not born [again]," which is the same as saying, "All that after the coming of Christ the Savior would enter into the Kingdom of the Heavens must be regenerated." And since infants are men, and as such need salvation, needing salvation they need also Baptism. And those that are not regenerated, since they have not received the remission of hereditary sin, are, of necessity, subject to eternal punishment, and consequently cannot without Baptism be saved. So that even infants should, of necessity, be baptized. Moreover, infants are saved, as is said in Matthew; {Matthew 19:12} but he that is not baptized is not saved. And consequently even infants must of necessity be baptized. And in the Acts {Acts 8:12; 16:33} it is said that the whole houses were baptized, and consequently the infants. To this the ancient Fathers also witness explicitly, and among them Dionysius in his Treatise concerning the Ecclesiastical Hierarchy; and Justin in his fifty-sixth Question, who says expressly, "And they are guaranteed the benefits of Baptism by the faith of those that bring them to Baptism." And Augustine says that it is an Apostolic tradition, that children are saved through Baptism; and in another place, "The Church gives to babes the feet of others, that they may come; and the hearts of others, that they may believe; and the tongues of others, that they may promise;" and in another place, "Our mother, the Church, furnishes them with a particular heart."
Orthodox today are, as we know, reluctant to say that children who die without baptism will be eternally separated from God--contemporary Catholics are also reluctant to say this (see, e.g.,
this report of the International Theological Commission)--but this does not mean that Orthodoxy has not taught this at some point in its history, even at the highest levels. It is precisely here that the notion of original guilt was, and is, invoked, namely, to justify this terrible situation. Once the possibility of the salvation of unbaptized infants is admitted there is no need to speak of original guilt.