This thesis aims to contribute to the existing gap in the research of religion in international relations by applying the theory of elite instrumentalism to the proxy conflict between Saudi Arabia and Iran. The analysis was able to demonstrate that the elites of both states have instrumentalized religion by utilizing concepts of Islamic rulership to legitimize their rule and justify their political actions. Iran has utilized the Shia Twelver concept of “Guardianship of the Jurist”, advocated by Ayatollah Khomeini during the Iranian revolution, to give Islamic jurists the same function as holy figures in Shia Islam. Saudi elites have legitimized their rule with the Wahhabi interpretation of Sunni Islam and the concept of “Head of the community”, which deems it sinful for subjects to oppose their Muslim ruler. By analysing fatwas, speeches, narratives and ideas being pushed by the elites of the countries, this study confirms that state elites have used religion to mobilize groups in the civil wars occurring in Yemen and Syria. Elites of both states have attempted to discredit each other to be able to expand their influence in the region and to assert their dominance by presenting themselves as rulers with the God-given right to rule.