The original (or "first") sin was committed by Adam and Eve (see Book of Genesis Chapter 3). Orthodoxy believes that, while everyone bears the consequences of the first sin, the foremost of which is physical death (in this world), only Adam and Eve are guilty of that sin (see Book of Ezekiel Chapter 18).
In contrast to Jewish exegesis of Genesis, Christianity has a Christological reading. We understand the depth of the Fall in the light of redemption. It is in the contrast of the old and new Adams that we understand what the significance of original sin has been.
Mortality is certainly a result of the Fall, but along with this also what is termed "concupiscence" in Augustine's writings -- this is the "evil impulse" of Judaism, and in Orthodoxy, we might say this is our "disordered passion" -- it isn't only that we are born in death, or in a state of distance from God, but also that we are born with disordered passion within us.
Orthodoxy would not describe the human state as one of "total depravity" (see Cyril Lucaris however). One writer has said that "if Latin babies are born blind, and Pelagian babies are born with 20/20 vision, then Greek babies are born in need of spectacles" (ref?).
Roman Catholic Teaching
Roman Catholicism teaches that everyone bears not only the consequence, but also the guilt, of that sin. This difference between the two Churches in their understanding of the original sin was one of the doctrinal reasons that led the Catholic Church to devise their dogma of the 'Immaculate Conception' in the 19th century, a dogma that is completely rejected by the Orthodox Church.(If this is historic RC teaching, it needs to be documented -- quotes from Romanides are not sufficient here. Certainly it is not the teaching today, see the CCC. Modern Orthodox polemics can be traced back to Fr. John Meyendorff (?)... earlier explanations tended to have a scholastic tone, both in Russia and in Greece)
For decades, at least, Orthodox teaching has often been contrasted to traditional Roman Catholic teaching on original sin.
Modern Roman Catholic teaching is best explicated in the Catechism of the Catholic Church, which includes this sentence: ""original sin does not have the character of a personal fault in any of Adam's descendants. It is a deprivation of original holiness and justice, but human nature has not been totally corrupted" (see Talk page for details).
The Roman Catholic Church has defined its teaching of original sin in multiple councils. The first of these was a Council of Orange in 529, which expanded upon the teachings of Augustine of Hippo, whose interpretation of "all dying in Adam"
Sources and further reading
- The Original Sin/Consequences of the Original Fall - by HG Bishop Kallistos Ware
- ORIGINAL SIN ACCORDING TO ST. PAUL - by the late V. Rev. Fr. John S. Romanides
- Original Sin/St. Augustine & Original Sin - Teachings of Orthodoxy - by Fr. John Matusiak, OCA: , , 
- Concerning the Original Sin - the current Coptic Orthodox viewpoint by HE Metropolitan Bishoy of Damietta (Arabic), and an Eastern Orthodox reply (Arabic)
- Original Sin, a short historical note - by Dr George Bebawi
- What are the differences between Orthodoxy and Roman Catholicism? - by Father Michael Azkoul
- CATHOLIC ENCYCLOPEDIA: Original Sin
- Original Sin - Wikipedia
- Banishment and Repentance of Adam and Every Christian by Saint Simeon the New Theologian
- Original Sin by Fr Alvin Kimel
- The First-Created Man: Seven Homilies by St. Symeon the New Theologian, trans. Seraphim Rose [ISBN:0938635115]
From Ephrem Hugh Bensusan's Razilaženje
- Original Sin in the Eastern Orthodox Confessions and Catechisms
- Ancestral vs. Original Sin: A False Dichotomy
- Ancestral Sin - Quotations From Orthodox Holy Fathers and Contemporary Authors
- Fr. George Mastrantonis on Ancestral Sin, excerpted from A New-Style Catechism on the Eastern Orthodox Faith for Adults by Fr. George Mastrantonis (St. Louis, MO: The OLOGOS Mission, 1969 ).
- Original Sin: The West-Haters Strike Back