added that a 'religious war' is not necessarily the same as a 'holy war' (bellum sacrum): 'After all, it is perfectly acceptable to suggest that a worldly prince, say, a Lutheran prince in Reformation Germany, engages in religious warfare using mercenary armies.' While a holy war needs to be authorised by a religious leader and fought by pious soldiers, a religious war does not, he reasoned. His definition of 'war of religion' thus became: Applicability of religion to war Some commentators have questioned the applicability of religion to war, in part because the word "religion" itself is difficult to define, particularly posing challenges when one tries to apply it to non-Western cultures. Secondly, it has been argued that religion is difficult to isolate as a factor, and is often just one of many factors driving a war. For example, many armed conflicts may be simultaneously wars of succession as well as wars of religion when two rival claimants to a throne also represent opposing religions. Examples include the War of the Three Henrys and the Succession of Henry IV of France during the French Wars of Religion, the Hessian War and the War of the Jülich Succession during the Reformation in Germany, and the Jacobite risings (including the Williamite–Jacobite wars) during the Reformation in Great Britain and Ireland. John Morreall and Tamara Sonn (2013) have argued that since there is no consensus on definitions of "religion" among scholars and no way to isolate "religion" from the rest of the more likely motivational dimensions (social, political, and economic); it is incorrect to label any violent event as "religious". Theologian William T. Cavanaugh in his Myth of Religious Violence (2009) argues that the very concept of "religion" is a modern Western concept that was invented recently in history. As such, he argues that the concept of "religious violence" or "religious wars" are incorrectly used to anachronistically label people and conflicts as participants in religious ideologies that never existed in the first place. The concept of "religion" as an abstraction which entails distinct sets of beliefs or doctrines is a recently invented concept in the English language since such usage began with texts from the 17th century due to the splitting of Christendom during the Protestant Reformation and more prevalent colonization or globalization in the age of exploration which involved contact with numerous foreign and indigenous cultures with non-European languages. It was in