Firstly, I’d mention that every religion is weaponized by reactionaries, not just islam. Surely, the reactionary manifestations of islam are more apparent, it is in part due to xenophobic propaganda, using liberal moralism to turn well-meaning people against a minority. Also the material conditions of majority muslim countries that prevent ideological progress where islam is the most alive, as the ideological superstructure is formed and used to justify the economic structure. Secondly, religions became so important because in feudal societies, most of the social life was organized by religion. The political discourse as well, was mostly structured by religion. But with the wave of bourgeois republicanism, religion was replaced by the republic to organize social life. That means, if you are not in a feudal society, religions are hollowed of their political function and become identities. As such, they may be used to justify reactionary sentiments but are far from being the reason of reactionary sentiments, as the analysis of structure and superstructure help us see.