Original sin is not actually in the Bible per se, but it is an interpretation of what the Bible teaches. It’s a doctrine typically credited to Augustine of Hippo (334-430), but he credits Irenaeus of Lyon, Bishop of Lyon (130-202). While the doctrine of original sin has taken many shapes over the centuries, it fundamentally declares that all sin is inherited from Adam, and in its truest form, all humans since Adam bear the guilt of his “original sin.”
Protestant reformers Martin Luther (1483-1546) and John Calvin (1509-1564) adopted and carried the idea even further. They considered that the guilt of original sin completely overwhelmed an individual’s free will to choose not to sin. In the Westminster Larger Catechism it is stated as, “All mankind…sinned in him [Adam], and fell with him in that first transgression… The sinfulness of that estate whereinto man fell, consisteth in the guilt of Adam’s first sin.” (Questions 25 and 26)
There’s much more that could be said about the origin and evolution of the original sin doctrine. For now, the question is does Scripture support its basic tenant of guilt for sin passed down from Adam to all of mankind?