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Jihad and Justice: Christian Just War Theory

September 3rd, 2007 | 3 min read

By Tex

There are three specific similarities between Christian and Islamic conceptions of just war: legitimate authorization, just cause, and right intentions. This week we’ll begin our comparison of these two religious points of view by examining the Christian conception of just war.

Augustine was one of the first Christian theologians to offer an in-depth and philosophically robust examination of the nature of the state and its relationship to Christianity, as well as the response of the Christian to war. His ideas influenced the fairly young Christian empire and provided the basic framework to later theologians and scholars to work within as they clarified and explicated Christian political theory. Augustine’s ideas were so influential that they still were being appealed to well into the thirteenth century. In his Summa Theologica, Aquinas readily refers to Augustine as he lays out a broad and concise systematic theology. Aquinas had a heavy impact on his age and on the development of theology and politics in the coming years. Both Augustine and Aquinas are valid sources to turn to in a study of Christian political and war theory because of the strong impact they both have had on Western thought—Augustine as the one who laid the broad foundation for the following generations to build upon, and Aquinas as the master who crystallized many subjects by bringing them into one unified whole.

Aquinas clearly spells out these three necessary components of just war in the Summa. Interestingly, each of these components can be traced back to Augustine and his thoughts on just war. By the time Aquinas presents them in the Summa they have been refined and made explicit; however, their elements can be found in various tracts and letters written by Augustine. Most obviously stated is the need for legitimate authorization. In his refutation of Manichean heresy, Contra Faustum, Augustine states, “A great deal depends on the causes for which men undertake wars, and on the authority they have for doing so; for the natural order which seeks the peace of mankind, ordains that the monarch should have the power of undertaking war if he thinks it advisable.” Aquinas picks up and expounds upon this statement writing, “…as the care of the common weal is committed to those who are in authority, it is their business to watch over the common weal of the city.”

Both Augustine and Aquinas recognize that the ontological equality of men necessitates that war only be undertaken with legitimate authority. No man, simply as a man, has the right to declare war on another. It is only by moving our attention from the rights and duties of the individual to those of the state that war can be justified. The only person who can legitimately declare war is the head of the state as he seeks to fulfill his obligation to provide for the common good of the people and to promote peace, harmony, and justice. The rights and duties of the state is not the subject under examination here, and a discussion of them has filled books, rather I want to simply point out that the Christian conception of just war is closely connected to a particular notion of nature of the state; and that a just war can only be prosecuted so long as the state, and its ruler, remains within the limits imposed by its nature and the obligations and rights this nature entails.

Coming soon…the second and third Christian conditions for war.

Other posts in the Jihad and Justice series:

Islamic and Christian Theories of War