What priestly office made Caesar the chief priest of Roman state religion?

The priestly office that made Caesar the chief priest of Roman state religion was the pontifex maximus. In the Roman Republic, this was the leading position in the College of Pontiffs, the body responsible for overseeing Rome’s official religious practices, sacred law, rituals, and calendar.

Julius Caesar was elected pontifex maximus in 63 BC after a highly competitive public election. The office brought enormous prestige and practical influence, including an official residence near the Roman Forum. It also strengthened Caesar’s public image at a time when religious authority and political power were closely connected.

The pontifex maximus was not the same as the rex sacrorum, who performed certain symbolic religious duties once associated with Rome’s kings. Nor was Caesar an augur or a flamen Dialis: those were separate priestly roles with different responsibilities. As pontifex maximus, Caesar later supervised the calendar reform that produced the Julian calendar. After his death, the office passed to Marcus Aemilius Lepidus and eventually became an imperial title.