People join ISIS for clear religious goals

The argument

Proponents of this position argue that the Islamic State's animating purpose is doctrinal, and that what draws recruits to it cannot be understood apart from that purpose. The group is centred on Salafism, a conservative interpretation of Sunni Islam with its roots in Wahhabism, another conservative interpretation currently championed by the Saudi Arabian government. The modern reformist Salafi movement is critical of what it deems misguided practices of Islam, and on this reading the Islamic State is best interpreted as a corrective effort within Wahhabism: an attempt to restore what its adherents take to be the authentic form of the tradition, and at the same time a violent rejection of the official Wahhabi doctrine of the Saudi state. The quarrel it picks is thus a quarrel over the correct content of the faith, which makes it a religious dispute before it is anything else. The declaration of a caliphate is what makes the point concrete for those who advance this argument. When its former leader Abu Bakr al-Baghdadi declared a 'caliphate' across Iraq and Syria on 28 June 2014, what was announced was not a grievance to be redressed or a territory valuable in itself but a formal state that would embody a return to the true origins of the Saudi-Wahhab project. On this view the declaration functions as the group's offer to prospective recruits, and the offer is doctrinal in its terms: what it holds out is a part in restoring a religious order, and the goal it states is clear and specific rather than vague. Proponents conclude that recruits who answer a call framed in those terms are best explained as pursuing the religious end the group advertises, and therefore that religion is the primary factor in its recruitment. It should be noted that this account infers what recruits seek from the organisation's own doctrine and declarations, rather than from direct evidence of the motives of individual recruits.

Premises

Counter-arguments

The core reasons why ISIS has interpreted Saudi Arabia of straying away from traditional Wahhabism is due to its collaboration with the West. While one could argue that religion is the ultimate cause, politics is the main facilitating factor that causes ISIS to act.

Rejecting the premises

[Rejecting P1] A doctrinal lineage explains the organisation's self-presentation, not what draws recruits; the premise describes the leadership's ideology and treats it as the motive of everyone who joins. [Rejecting P2] Declaring a caliphate is an act of state-building as much as of religion, and the counter's point is that the stated grievance — Saudi collaboration with the West — is political; the argument offers no evidence about recruits' own reasons, which is what the question asks.