Original Sin as Inherited Guilt Removed in Baptism

Augustine of Hippo built the developed doctrine of original sin during a running fight with Pelagius, a British monk teaching in Rome around 400 CE who held that Adam's sin harmed only Adam, leaving every later person born morally neutral and fully capable of choosing good without special grace. Augustine, most fully in On Nature and Grace, answered that Adam's guilt is transmitted to the whole human race, so that every infant is born already guilty and in need of the grace baptism confers, not merely bad example to be resisted by will.

One text carried unusual weight in the argument. The Latin Vulgate rendered Romans 5:12 as saying death spread to all because in whom, in quo, all sinned, read as all humanity sinning covertly in Adam himself. The Greek behind it, eph ho, more naturally means because or in that all sinned, describing each person's own sin as the cause of death rather than participation in Adam's single act. Augustine, who read Paul in Latin and had limited Greek, leaned on the stronger reading the mistranslation supplied.

The Council of Carthage condemned Pelagius's teaching in 418 and the Western church followed Augustine's account, formalized centuries later at the Council of Trent and still confessed in the Catholic Catechism. Eastern Christianity took a different route from the same starting texts, holding that Adam's sin left humanity mortal and disordered without holding each descendant personally guilty of Adam's own act, a distinction Orthodox theology has pressed as the real fault line between the two halves of the old empire's church.

The Council of Trent's fifth session, closed on June 17, 1546, did more than answer Pelagius. Its canons defined that baptism truly and properly takes away the guilt of original sin in every person baptized, infant or adult, and that nothing remains afterward that answers to the true and proper definition of sin. What does remain, the council said, is concupiscence, a disordered inclination toward sin that baptism does not erase. Trent insisted this leftover inclination is not itself sin in the strict sense, only fuel for temptation that a baptized person can resist by grace. That distinction carries consequences the doctrine of guilt alone does not explain. Because the guilt is judged real and inherited rather than merely imitated, the church baptizes infants without delay rather than waiting for an age of reason, since an unbaptized infant is held to die still bearing Adam's guilt. The same logic reaches further still: if every human being but one inherits this guilt at conception, Mary's own conception needed a separate exemption to remain sinless from the first moment of her existence, which is exactly the claim Pope Pius IX defined as the Immaculate Conception in 1854, three centuries after Trent had first drawn the line the later dogma depends on.