Ottoman Caliphate a bit lacking in the moral authority department, it would seem

Explanation: During WW1, the Ottoman Sultan, who still formally claimed the religious authority of the Caliph, made an announcement to the faithful Muslims of the world to engage in holy war (jihad) against the powers aligned with the Triple Entente.

This did have some effect, especially where the Triple Entente was already unwelcome - such as in North Africa, Central Asia, the Indian subcontinent, and parts of the Middle East. But Muslims in long-established Entente powers met the announcement with an overwhelming shrug - the Ottoman Empire attempting to declare jihad in support of their Christian German and Austro-Hungarian allies attempting to subdue largely other Christians did not seem particularly compelling to most European Muslims outside of the Ottoman Empire itself.

To add insult to injury, when Romania entered the war on the side of the Entente, its relatively small Muslim population still turned out to volunteer for service in the Romanian military - including against the Ottoman Empire itself.