His Eminence is a historical style of reference for high nobility, still in use in various religious contexts.
A longer, and more formal, title is "His (or Your when addressing the cardinal directly) Most Reverend Eminence".[a]
When the Grand Master of the Military Order of the Knights of Malta, the head of state of their sovereign territorial state comprising the island of Malta until 1797, who had already been made a Reichsfürst (i.e., prince of the Holy Roman Empire) in 1607, became (in terms of honorary order of precedence, not in the actual church hierarchy of ordained ministers) the most senior official after the most junior member of the Cardinals in 1630, he was also awarded the hybrid style His Most Eminent Highness, to recognize his status as a type of prince of the Church.
While the term is shunned by many individuals of other faiths or denominations of Christianity, the title is officially maintained in international diplomacy without regard for its doctrinal, philosophical and theological origins.
Archbishops in the Eastern Orthodox Church are addressed with the styles of "Beatitude" or "Eminence". The Ecumenical Patriarch of Constantinople is styled "His All-Holiness", and so is, exceptionally, the Metropolitan Bishop of Thessaloniki. The patriarchs of Alexandria, Antiochia and Jerusalem, as well as the Georgian, Serbian, Bulgarian and Russian patriarchs are referred to as "His Holiness", while Rumanian Patriarchs are referred to as "His Beatitude".
It is also used, informally (perhaps as a rendering of an oriental style), in Islam for highly honorable religious leaders. For example, an Imam of the Sunni Barelwi school of thought, Moulana Syed Madani Mia, is often addressed with this title, along with individuals such as Moulana Khushtar Siddiqi of Mauritius, although these titles are, in essence, unofficial. Beyond this, the traditional rulers of the sub-national states of the Fulani, Hausa, Nupe and Kanuri peoples of Nigeria use the style as an alternative to the HRH style that is usually used by the country's royal monarchs, highlighting by so doing their positions as spiritual as well as temporal leaders.