Hamartiology is the branch of Christian theology that is concerned with the study of the sin.

Substantial branches of hamartiological understanding include the doctrine of original sin, which was popularized by St. Augustine. Augustine taught that all the descendents of Adam and Eve became guilty of Adam's sin without their own personal choice.

In contrast, Pelagius argued that humans enter life as essentially tabula rasas. The Fall that occurred when Adam and Eve disobeyed God was held by this group to have effected humankind only minimally. But few continue to hold the hamartiological viewpoint of Pelagius.

A third branch of thinking takes an intermediate position, arguing that after the Fall of Adam and Eve, humans are born impacte by sin such that they have very decided tendencies toward sinning (which by personal choice all accountable humans but Jesus soon choose to indulge).

The degree to which humankind is impacted by the Fall determines very largely the role of human participation in the conflict between the forces of good and of evil. Hence, hamartiology plays a central role in how Christians understand what salvation means and how they should relate to their role as projected in the Apocalyptic Scriptures (mostly the Bible books of Daniel and Revelations).