This thesis seeks to uncover the relationship between the religious affiliation of civil war combatants and religious civil war duration. I argue that religious civil wars involving Islamic groups last longer than conflict involving groups of other religious traditions due the to heightened role of issue indivisibility and the presence of structural factors specific to the Islamic religion. Although the statistical analyses yielded indeterminate findings that ran counter to my theory and hypotheses, qualitative analyses provided support for the mechanisms that I theorize result in wars involving an Islamic group to last longer than conflicts between groups of other religious traditions.