Jupiter Dolichenus was a Roman god whose mystery cult was widespread in the Roman Empire from the early-2nd to mid-3rd centuries AD. Like several other figures of the mystery cults, Jupiter Dolichenus was one of the so-called 'oriental' gods; that is Roman re-inventions of ostensibly foreign figures in order to give their cults legitimacy and to distinguish them from the cults of the traditional Roman gods.
Like the other mystery cults (including the other pseudo-oriental ones), the cult of Jupiter Dolichenus gained popularity in the Roman Empire as a complement of the open 'public' religion of mainstream Roman society. Unlike the Roman public cults, but like the other mysteries, the temples of the cult of Jupiter Dolichenus were nominally closed to outsiders and followers had to undergo rites of initiation before they could be accepted as devotees. As a result, very little is known about the cult's beliefs and practices from the few clues that can be obtained from the sparse iconographic, archaeological or epigraphic evidence.
The cult gained popularity in the 2nd century AD, reached a peak under the Severan dynasty in the early 3rd century AD, and died out shortly thereafter. At least nineteen temples (including two discovered in 2000) are known to have been built in Rome and the provinces which, while substantial, is far below the popularity enjoyed by the comparable pseudo-oriental cults of Mithras, Isis or Cybele.
Until the late 20th-century, Roman exoticism was usually taken at face value, and Jupiter Dolichenus was therefore like the other pseudo-oriental figures also assumed to have really been a Roman continuation of an oriental figure. In the case of Jupiter Dolichenus, the exoticism was attributed to an interpretatio romana derivation from a semitic Hadad-Baal-Teshub cult, which had its cult center on a hill (37.1278°N 37.3453°W) near Doliche, 30 Roman Miles west of Samosata on the Euphrates, in the Commagene in eastern Asia Minor (The present-day name of the hill is Baba Tepesi, "the Hill of the Father (Teshub)". Historical Doliche is on a height now known as Keber Tepe, just west of Dülük, Gaziantep Province, Turkey). It is from the city of Doliche that the epithet 'Dolichenus' "of Doliche" was adopted. However, since the 1980s, it has become increasingly evident that the exotic gloss the Romans gave to their so-called 'oriental' gods was mostly superficial, and based primarily on Roman perceptions (hearsay and their own imagination) of what the foreign gods were like. Accordingly, in the context of Roman religion, the term 'oriental' no longer carries much weight and is now mostly only used as an archaeological docket tag. This development applies to all Roman 'oriental' gods equally.
The cult of Jupiter Dolichenus is especially difficult to assess in this respect because the archaeological finds at Dülük indicate that, at some point, Roman material was exported to Doliche, thus obscuring the distinction between Roman and native cult there. These scholastic issues notwithstanding, the Romans perceived Jupiter Dolichenus as 'Syrian', and that perception, not the reality, influenced the Roman world. Reinvented or not, the Roman cult appears to have been informed by Baal's roles as a national god and as a 'king' god (i.e. the senior-most of his pantheon), both aspects also being features of Roman Jupiter. How much doctrine (if any) the Romans borrowed remains unknown.
The earliest traces of the cult of Jupiter Dolichenus appear in the early 2nd-century, perhaps as a by-product of contact between Roman and Commagenian troops during the allied Roman-Commagenian campaigns against the Kingdom of Pontus in 64 BC, but perhaps also as a product of greatly embellished (or even freely invented) travel accounts or colportage which circulated around the Mediterranean rim in the Hellenistic and early Roman periods. The earliest dateable evidence for the Roman cult is an inscription from Lambaesis in Numidia (in present-day Algeria), where the commander of Roman troops and de facto governor dedicated an altar in 125 AD. The cult is next attested in Rome, during the reign of Marcus Aurelius (r. 161–180) when a temple to Jupiter Dolichenus was built on the Caelian Hill. Not much later, the cult is attested in Germany where a centurion of Legio VIII Augusta dedicated an altar in 191 at Obernburg in Germania Superior . A large number of dedications then occur under Septimius Severus (r. 193–211) and Caracalla (r. 198–217), which represents the high point of the cult. A once-held idea that the cult of Jupiter Dolichenus received imperial support, in particular from the Severan dynasts (who were of Syrian-African descent), is no longer followed. Another older notion that Jupiter Dolichenus was the tutelary divinity of the army is also obsolete.
Unlike the other pseudo-oriental mystery cults, the worship of Jupiter Dolichenus was very fixed on its 'Doliche'/'Syrian' exoticism and identity, which contributed to the cult's demise. Through an identification with the Severan dynasty (which was perceived to be 'Syrian' as Caracalla was half Syrian and spent much of his reign in the eastern provinces), following the assassination of Alexander Severus in 235 the cult perhaps became a target as part of an 'Illyrian reaction' against the fallen 'Syrian' dynasty and its supporters. The archaeological record reveals violent destruction of all known Dolichenus temples in the provinces on the Rhine and Danube during the reign of Maximinus Thrax (r. 235–238). The Thracian emperor is known to have filled his coffers from sanctuaries, and the cult of Jupiter Dolichenus was an easy target since it was not very widespread. However, the destruction of the sanctuaries in the Rhine/Danubian provinces was not the end of the cult, either in those provinces or anywhere else, and several monuments date to the next two decades.
However, in 253 or 256, the Sassanid emperor Shapur I captured and sacked Doliche. It appears that with the loss of Dolichenus' ostensible main sanctuary, the god was permanently discredited in terms of his perceived power, and evidence of the cult ceased thereafter. The cult had tied itself so firmly to the sanctity of Doliche and to the oriental nature of the god that it had never achieved the universality that it needed in order to survive the loss. The last known Dolichenus monument is from the Esquiline Hill temple and dates to the reign of Gallienus (r. 253–268). Several monuments were formerly thought to be of a later date, but those estimates are now obsolete.