Original sin is the Augustine Christian doctrine that everyone is born a sinner. This means that, through the fact of birth, we are born with a built-in urge to do bad things and to disobey God. Theologians have characterized this condition in many ways, seeing it as ranging from something as insignificant as a slight deficiency, or as the total depravity or automatic guilt of all humans through collective guilt. Original sin is not just this defect in human nature. It is also the 'condemnation' that goes with that fault.

    The biblical bases for the belief are traditionally found in a mistranslated passage in The Epistle to the Romans (Romans, 5:12-21) "Therefore, just as sin entered the world through one man, and death through sin, and in this way death came to all people, because all sinned... " in Genesis 3 (the story of the expulsion of Adam and Eve from the Garden of Eden), and in a line in Psalm 51:5 ("I was brought forth in iniquity, and in sin did my mother conceive me").  

     The doctrine of original sin is an important doctrine within the Roman Catholic Church. It began to emerge in the 3rd century, but only became fully formed with the writings of Augustine of Hippo (354–430), who was the first author to use the phrase "original sin" (Latin: peccatum originale). Influenced by Augustine, the councils of Carthage (411-418 AD) and Orange (529 AD) brought theological speculation about original sin officially into the Church.

     Protestant reformers such as Martin Luther and John Calvin asserted original sin was the same as concupiscence (or "hurtful desire"), claiming that it persisted even after baptism and completely destroyed the will to do good, proposing that original sin was the complete loss of free will except to sin.  Instead, the Catholic Church declares that "Baptism, by imparting Christ's grace, erases original sin and turns a man back towards God, but the consequences (of Original SIn) persist in man and summon him to spiritual battle", and that "weakened and diminished by Adam's fall, free will is yet not destroyed in the race."

An explanation for the evils of the world

Some Christians believe that original sin explains why there is so much wrong in a world created by a perfect God, and why people need to have their souls 'saved' by God.

A condition you're in, not something you do

Original sin is a condition, not something that people do: It's the normal spiritual and psychological condition of human beings, not their bad thoughts and actions. Even a newborn baby who hasn't done anything at all is damaged by original sin.

The sin of Adam

In traditional Christian teaching, original sin is the result of Adam and Eve's disobedience to God when they ate a forbidden fruit in the Garden of Eden.