What is Orginal Sin?

[Ryft]

I'd like to hear from Christians what original sin is, because I can never understand why God would allow the sin of a father (Adam) to be committed to the son (humanity). I've heard reasons from others to believe why this is wrong, but can anyone prove why it is right?

The question of original sin is somewhat difficult to discuss with non-Christians because it is a theological issue that is settled exegetically (i.e., study of the biblical texts); if one denies the Scriptures as divine revelation, the whole matter becomes rather moot (but their denial is a product of original sin). Outside of the biblical texts I suppose one could define original sin however they like, although the fact that such a person is talking about original sin at all would be quite odd, since it is quintessentially a biblical concept. While the term itself is not found in the Scriptures—it was coined by Augustine of Hippo—the concept is deeply biblical, rooted in the theology of salvation (soteriology).

There is an aphorism penned by Paul E. Little that captures the essence of original sin: "We are not sinners because we sin; we sin because we are sinners." Original sin means quite simply sin derived from our origin; biblically and theologically that origin is "in Adam," who is the federal representative of all mankind as imago Dei. It is not so much that we are all held accountable for Adam's sin, as your question alluded to, as that all mankind is fallen as sinners because Adam, our federal head in the economy of salvation, fell into sin; i.e., from a sinful origin comes a sinful lineage, a condition which produces in man every sort of sin. In this same theology of salvation we have Jesus Christ, described in this context as the "second Adam" (cf. the theological dichotomy revealed in the New Testament gospels and epistles); that is, all mankind is represented in one of two camps, such that those who are not "in Christ" (him being their federal head) remain "in Adam" (him being their federal head). So that is the meaning of original sin: sin derived from our origin, condemned "in Adam" as sinners until we are justified "in Christ" as redeemed.