SOL INVICTUS . Worship of the sun god, Sol, was known in republican Rome, but it was of minor importance. In imperial Rome, however, in the third century ce (the last century of pagan Rome), the cult of the sun god became a major and, at times, dominant force in Roman religion. The cult of the Syrian sun god from Emesa, installed at Rome under the emperor Elagabalus (218–222), was short-lived, but in 274 the emperor Aurelian began a vigorous campaign of propaganda celebrating the sun god as the exclusive protector of Rome's imperial might. Under the epithets oriens ("the rising one"), invictus ("the invincible one"), and comes Augusti ("comrade of Augustus"), Sol was hailed as "the rising sun who dispels the forces of evil," as "invincible conqueror of Rome's enemies," and as the "companion and guardian deity of the emperor."
Numismatic iconography, the primary source for this propaganda campaign, portrayed Sol wearing the radiate crown and holding the globe, symbol of world rule, in his hand, while the vanquished enemy cowered at his feet. This campaign was continued with particular force by the emperors Probus (276–282) and Constantine (306–337). As late as 324, coins of Constantine celebrated Sol as the grantor of imperial power to the emperor. Only thereafter, in the last thirteen years of Constantine's reign, did references to Sol and to all other pagan divinities disappear from the coins.
A variety of influences contributed to the importance of Sol Invictus, the Invincible Sun, in imperial ideology of the third century ce. It was an age of religious syncretism and growing monotheism, when philosophers and common people alike increasingly viewed all divinities as emanations of one supreme divine force. Sol was equated with Mithra, and as Sol Invictus Mithra was regarded as the most powerful and most immediate divine mediator between humans and the invisible majesty of the supreme god. Thus Sol Invictus was the natural associate of the emperor, who ruled the earth as the vicegerent of the supreme god. The symbolism of the Pantheon built by the emperor Hadrian (117–138) had already intimately linked the emperor and Sol as the visible manifestations of the beneficent and omnipotent supreme god. The cult title Invictus was a natural outgrowth of this relationship. First attested for Sol in 158 ce, it was almost certainly borrowed by the god from the emperor's own panoply of titles.
The pervasive influence of imperial propaganda, together with the popularity of Mithraism in the third century, assured Sol Invictus an influence upon other divine formulations, Christian as well as pagan. A vault mosaic of the third century in the tomb of the Julii under Saint Peter's portrays Christ as Sol, rising in his chariot. The words of the Christmas Mass in the Missale Gothicum hail Christ as Sol Iustitiae ("sun of justice"), while the traditional date of Christmas, first attested in the fourth century, is hardly unrelated to the fact that December 25 was celebrated as the birthday of Sol Invictus Mithra.
Gaston H. Halsberghe's Cult of Sol Invictus (Leiden, 1972), edited by Maarten J. Vermaseren as volume 23 of "Études préliminaires aux religions orientales dans l'empire romain," is an uncritical collection of evidence and is to be used with caution. See my review in Byzantine Studies 2 (1975): 81–82. The significance of the cult of Sol Invictus in imperial ideology is treated with great insight by Ernst H. Kantorowicz in his article "Oriens Augusti: Lever du Roi," Dumbarton Oaks Papers 17 (1963): 117–177. For a more recent discussion, see my Princeps a Diis Electus: The Divine Election of the Emperor as a Political Concept at Rome (Rome, 1977), pp. 238–243, 281–315, and my article "The Theology of Victory at Rome," in Aufstieg und Niedergang der römischen Welt, vol. 2.17.2 (Berlin and New York, 1981), pp. 804–825.
Chirassi Colombo, Ileana. "Sol invictus o Mithra. (Per una rilettura in chiave ideologica della teologia solare del mitraismo nell'ambito del politeismo romano)." In Mysteria Mithrae. Atti del Seminario Internazionale su La specificità storico-religiosa dei misteri di Mithra, con particolare riferimento alle fonti documentarie di Roma e Ostia, Roma e Ostia, 28–31 marzo 1978, ed. by Ugo Bianchi, pp. 649–672. Leiden, 1979.
Clauss, Manfred. "Sol invictus Mithras." Athenaeum 58 (1990): 423–450.
Fauth, Wolfgang. Helios Megistos: Zur synkretistischen Theologie der Spätantike. Leiden, 1995.
Halsberghe, Gaston H. "Le culte de Deus Sol Invictus à Rome au III siècle après J.C." In Aufstieg und Niedergang der Römischen Welt 2.17.4, pp. 2181–2201. Berlin and New York, 1984.
MacDowall, David W. "Sol invictus and Mithra. Some Evidence from the Mint of Rome." In Mysteria Mithrae. Atti del Seminario Internazionale su La specificità storico-religiosa dei misteri di Mithra, con particolare riferimento alle fonti documentarie di Roma e Ostia, Roma e Ostia, 28–31 marzo 1978, edited by Ugo Bianchi, pp. 557–569. Leiden, 1979.
Turcan, Robert. Héliogabale et la sacre du soleil. Paris, 1985.
Wallraff, Martin. Christus verus sol. Sonnenverehrung und Christentum in der Spätantike. Münster, 2001.
J. Rufus Fears (1987)