Original sin is known in two senses: the Fall of Adam as the "original" sin and the hereditary fallen nature and moral corruption that is passed down from Adam to his descendants. It is called "original" in that Adam, the first man, is the one who sinned and thus caused sin to enter the world. Even though Eve is the one who sinned first, because Adam is the Federal Head (representative of mankind), his fall included or represented all of humanity. Therefore, some hold that original sin includes the falling of all humanity. Some see original sin as Adam's fallen nature being passed to his descendants. "Therefore, just as through one man sin entered into the world, and death through sin, and so death spread to all men, because all sinned--" (Rom. 5:12).
Original sin is not a physical corruption but a moral and spiritual corruption. It could be compared to the Reformed Doctrine of Total Depravity which states that sin has touched all parts of what a person is: heart, mind, soul, will, thoughts, desires, etc.
There has been much debate over the nature of the sin of Adam and how it affected mankind. Pelagius taught that Adam's sin influenced the human race only as a bad example and that all people are born in the same state as Adam was before his fall. Augustine taught that men inherit natural corruption from Adam.1
At the return of Christ and the resurrection of all Christians, the sin nature will be eradicated.
- 1. Harrison, Everett, ed., Baker's Dictionary of Theology, Grand Rapids: Baker Book House, 1960, p. 488.