The Relationship of Faith and Fighting

When, if ever, is it acceptable to link faith and fighting? And how are we to distinguish a Christian or a Muslim fighting for their faith from someone who happens to be Muslim or Christian fighting for some other reason? Furthermore, if they claim to be fighting for their faith, how do we judge when those claims have some justification within their own faith tradition? This last point requires, at the very least, familiarity with the foundational texts of each faith and how they have been interpreted. Martin Luther (d. 1546) and Ibn Taymiyya (d. 1328/728) are two famous examples of the many Christians and Muslims who have thought about the relationship of faith and fighting.

Martin Luther, writing in the context of possible invasion by the Ottomans, insisted that Christians can fight to defend their land, but not to defend or advance the Christian message. In this he clearly opposes the approach seen in the Crusades. Fighting for the faith has a more explicit place in Muslim writings. Ibn Taymiyya is often seen as the Muslim writer who justifies fighting in the name of faith in a particularly wide range of circumstances - though just how wide has recently been disputed. Debate continues over whether Ibn Taymiyya’s call for Muslims to resist the Mongols, who had converted to Islam, was based on the need to overthrow an unfaithful Muslim regime, or to repel what was essentially a foreign invading power.

See Martin Luther On War Against the Turk
Rudolph Peters, Jihad in Classical and Modern Islam (Princeton: Markus Wiener, 1996), pp. 44-54 [gives a translation of Ibn Taymiyya on Jihad].
Yahya Michot Muslims Under non-Muslim Rule (Oxford: Interface, 2006) [shows how Ibn Taymiyya is used to justify different positions].