In other words, what the recording shows is Mr. Baghdadi’s donning the mantle of anticolonial redeemer and trumping jihadist rivals, like the Qaeda leader Ayman al-Zawahiri, in a war of words and symbols. Osama bin Laden was said to have been nervous about the quality of his preaching, fearing that recordings would document his mistakes. Mr. Baghdadi, who according to jihadist websites comes from a learned family and has a doctorate in Islamic studies, is turning that training to his advantage.

The style of his address is formal, loosely rhyming classical Arabic infused with Quranic words and phrases. The form is a “letter addressed to those undertaking jihad and the Islamic community.” The mode of persuasion is to adduce scriptural truths to induce action — above all that Muslims are to fear God and fight on God’s behalf. In these and other respects, the address bears striking similarities to the letters, sermons and speeches of Islam’s caliphates in the seventh, eighth and ninth centuries, powerful empires that legitimized their rule by claiming succession from the Prophet Muhammad.

The medium being the message, its symbols are deliberately archaic. When Mr. Baghdadi calls metaphorically for the conquest of “Rome,” he’s signaling to his audience command of a repertory of tropes and symbols: When early Muslim caliphs announced their ambition to conquer “Rome,” they had in mind Constantinople (now Istanbul) — the “new Rome” as it was then understood, the Greek-speaking capital of Byzantium, and the caliphate’s only rival for religious and political supremacy.

The few contemporary references in Mr. Baghdadi’s remarks — to Burma, America, the veil in France, democracy, secularism — are not intended to show off any command of current affairs, but are gestures intended to illustrate the mythic conflict between belief and unbelief, between God’s justice and human tyranny.

Mr. Baghdadi is introduced in the recording as “our master, commander of the faithful, Abu Bakr al-Husayni al-Qureishi al-Baghdadi.” The phraseology is at once formulaic (“commander of the faithful” was the conventional title of address for a caliph) and cynical. The nom de guerre “Abu Bakr” recycles the name of Muhammad’s father-in-law and Islam’s first caliph, chosen by contemporaries over the objection of those who favored Muhammad’s son-in-law Ali — the Shiites. Meanwhile, Mr. Baghdadi’s alleged descent from the Qureish tribe fulfills one of the qualifications for the office held crucial by pre-modern Muslim scholars, who required that caliphs share Muhammad’s kinship. Baghdad, of course, was the principal seat of the caliphate from the eighth through the 13th centuries, when it was conquered by the Mongols.