From the 7th century until early in the 20th century, when this title was abolished, what was the title of the spiritual leader of all Islam?

The title for the spiritual and political leader of the Muslim community, or ummah, was Caliph. The word itself comes from the Arabic "khalifa," meaning "successor" or "deputy," as the role was established to designate the successor to the Prophet Muhammad after his death in 632 CE. The first four leaders to hold this position are known as the "Rightly Guided Caliphs" and are revered for establishing the foundations of the Islamic state.

Over the centuries, the Caliphate evolved from a single, unified office into a more complex institution. Following the initial period, major dynasties like the Umayyads in Damascus and later the Abbasids in Baghdad held the title. At various times, competing caliphates even existed simultaneously, such as the Fatimids in Egypt and the Umayyads of Córdoba in Spain, each claiming leadership over the faithful. The last widely recognized claim to the title was held by the sultans of the Ottoman Empire.

The institution, which had existed for nearly 1,300 years, came to a formal end in the early 20th century. Following the defeat and collapse of the Ottoman Empire after World War I, the new secular government of the Republic of Turkey, under the leadership of Mustafa Kemal Atatürk, officially abolished the Caliphate in 1924. This act brought an end to one of the most significant political and religious institutions in Islamic history.