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 (CCC 419). 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.
The Catechism of the Catholic Church (CCC) is easily misunderstood in regards to this topic, especially since the Roman Catholic faith provides a clear distinction between Original Sin and personal sins which is not easily identifiable to non-Catholics. The Catechism states "original sin does not have the character of a personal fault in any of Adam's descendants" ( CCC 405). But when reading this passage, one needs to identify that this passage tells us that no person besides Adam was personally responsible for his own sin. Only Adam had the intent to sin, not the rest of humanity and thus the rest of humanity could not have inherited Adam's personal sin (Deuteronomy 24:16; Ezekiel 18). But the catechism goes on to say "We therefore hold, with the Council of Trent, that original sin is transmitted with human nature, 'by propagation, not by imitation'" (CCC 419). This means, while the rest of mankind is not personally responsible for Adam's sin, they still bear the "guilt" of that sin by propegation or inheritence which needs to be forgiven in baptism. This guilt is seen as being equal to personal mortal sins on the day of Judgement.
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