adoptionism: The view that Jesus was a human being adopted as son of God at his baptism.
adversus Iudaeos (also contra Iudaeos): A theological rhetoric that constructs Christian identity by juxtaposing it to a negative conception of Jews and Judaism.
allegory: From the Greek “other-speak,” a technique of reading that ascribes meanings to a text that are symbolic or “hidden,” often associated with a “spiritual” meaning as opposed to a literal/“fleshly” one.
apocalyptic eschatology: Knowledge, often esoteric, concerning last things before the end of normal history and the establishment of the Kingdom of God. Certain themes, like the battle between good and evil or the resurrection of the dead, characterize Jewish restoration theology more generally. The difference is that apocalyptic eschatology asserts that the End is near. In its Christian iterations, it asserted the imminent Second Coming of Christ.
Arianism: A theology about the nature of Jesus’s preexistence as divine Son that distinguishes him from God the Father by way of subordination: Christ derives from the father but is not equal to him. “Arianism” later functioned to label any position that differed from that asserted in the Nicene Creed.
asceticism: From the Greek askesis meaning “athletic training,” a strict self-discipline that minimizes food, sex, sleep, or physical comfort for the purpose of spiritual advancement.
Barnabas: A mid-second-century sermon, presented as an epistle, that reads Jewish scriptures allegorically to promote the author’s view of Christianity as prior and spiritually superior to Judaism.
Chalcedon: An ecumenical church council convened by the emperor in 451 to settle questions on the divine and human natures of Christ. It affirmed that Christ had two natures, both fully divine and fully human, as opposed to a single nature. The council’s decision was rejected by “one-nature” (Miaphysite) Christians in Egypt and in Syria.
Christology: Theological reflection on the nature and work of Christ. Many of the categories are drawn from Greco-Roman philosophy.
confessors: Christians who were imprisoned, prepared for martyrdom, but who were subsequently released. On this merit, they claimed the authority to forgive sins.
Constitutio Antoniana: The edict pronounced by the emperor Caracalla in 212 granting all free residents of the empire the status of citizens of Rome.
cosmos: Greek “order,” the term for the organization of the geocentric universe, the earth being surrounded by the spheres of the sun and moon, the five planets known to antiquity, and the sphere of the fixed stars.
cult of the saints: Celebrations and worship over the graves or relics of martyrs.
daimon (pl. daimones): The term for lesser gods, located in the cosmos especially in the sublunar realm.
demiurge: The go-between god of ancient cosmologies, who acted as the agent of the highest god in organizing the physical universe.
demons: Derived from daimones, demons were ethically demoted in Christian thought to always refer to maleficent beings, the root cause of heresies and persecutions.
Diaspora: Greek “dispersion,” a Jewish term relating to all lands outside of territorial Israel.
Docetism: From the Greek dokeo, “to appear”; a term claiming that Christ only appeared to have a human body, but did not in fact have one. Proto-orthodox heresy hunters ascribed this position to followers of Valentinus and of Marcion.
Elvira: A church council gathered in Spain circa 303 that detailed behavioral rules for Christians interacting with heretics, pagans, and Jews. Behaviors were to be policed through withholding of sacraments.
ethnos (pl. ethnē): The word for people group, corresponding to the Hebrew goyim. In Jewish writings it usually refers to non-Jewish nations who worship non-Jewish gods. It is often translated as “gentile,” but it carries a religious freight too, hence the translation “pagan.”
Gnostics: Greek “knowers,” from gnōsis (“knowledge”), a term used to designate those forms of Christianity that emphasized esoteric knowledge of a highest god and a spiritual cosmos above the cosmic god and the physical universe. The cosmic god was often associated with the divinity depicted in Genesis, while the highest god was considered the father of Christ. This way of thinking does not describe a discrete group, but rather a mood within evolving second-century Christianities.
Goths: A Germanic people on the northeastern border of the empire, divided into East (Ostrogothic) and West (Visigothic) populations. They were often federated to Rome for military purposes but became increasingly independent within the western half of the empire in the course of the fourth century. Goths observed a form of Christianity characterized by Nicene critics as “Arian.” Their leader Alaric sacked the city of Rome in 410.
heresy: Derived from hairesis, the Greek word meaning “school” or “sect.” Heresy evolved in the second century to mean those Christian groups whom a proto-orthodox writer deemed as “deviant” from apostolic tradition.
homodoxia, homonoia: Derived from the Second Sophistic, a philosophical and rhetorical movement within first- through third-century Greco-Roman culture; the terms mean “unanimity” and “concord,” attributes associated with true philosophy.
homoousia: “Same essence” or “substance”; the philosophical term was applied by Christian theologians to describe the relation between God the Father and God the Son. It makes a maximal claim for the divinity of Christ, being “of the same substance” as the Father.
homoiousia: “Similar essence” or “substance,” stating that Christ is “like” but not identical to God the Father.
hylē: Unformed matter, coeternal with the high god in Greek cosmologies, which formed the material substratum of the organized universe.
hypostasis: A philosophical term indicating an independently existing entity, sometimes translatable as “person” or as “substance.” For classical theology, the Trinity was defined as a single ousia (“substance” or “essence”) in three hypostases (“persons”).
logos: “Word” or “reason” or “speech”; Logos in Jewish and Christian theological systems represents the divine aspect or agent through which the highest god creates. Christian systems identify the Logos with the preexistent Christ.
Maccabean Revolt: The war in Judea over degrees of assimilation to Greek culture fought between Syrian Greeks under the Seleucid dynasty and Judeans led by the Hasmonean family under Judah Maccabee, 167–164 BCE.
Manichaeism: A third-century form of Christianity founded by Mani; Manichaeism posited two eternally contesting cosmic realms, Light and Darkness, with the human being as a miniature instance of this struggle.
Miaphysite Christology: The view that Christ had a single, divine nature as opposed to two independent natures, divine and human. Also referred to as “Monophysite” Christology.
millenarianism: The belief that the saints will rise in a first resurrection to reign with Christ on earth for one thousand years.
millennial week: A way to calculate the arrival of the Second Coming of Christ; the millennial week stipulated that time would continue from creation in six thousand-year units (“days”), until the dawning of the thousand-year Sabbath and the terrestrial reign of the saints. In this calculus, Christ was held to have been born in the year 5500 since creation, making the appointed end-time correspond to our year 500 CE.
Milvian Bridge: The location in Rome for the battle between Constantine and Maxentius. Constantine attributed his victory there to the agency of the Christian god.
Mishnah: Hebrew “repetition,” a body of orally transmitted Jewish law compiled in Hebrew circa 200 CE. This becomes a core text of rabbinic Judaism.
Montanists: A late second-century Christian movement of the “New Prophecy” formed in Phrygia and holding to a belief that the End, and God’s kingdom, were imminent. Montanists believed that the Holy Spirit was the source of their continuing revelations.
Nag Hammadi library: Those second-century, often esoteric Christian texts, translated by the fourth century from Greek into Coptic, hidden at Nag Hammadi in Egypt.
Nicaea: The council convened by Constantine in 325 to decide, among other issues, on the nature of the divinity of Christ. The Nicene Creed, eventually derived from the work of the council, becomes the index of imperial orthodoxy in 380, mandated by the emperors Gratian and Theodosius I in the Edict of Thessalonica.
ousia: “Essence” or “substance,” a term used to articulate the relation of God the Son to God the Father. Homousian theologians, most associated with Athanasius, held that Christ was “of the same ousia” as God; those associated with Arius held that Christ’s ousia was similar to but not identical with that of God the Father.
pax deorum: “Peace of the gods,” the pact between good government, thus proper religion, on earth and deities in heaven. Under Constantine, the concept will shift to the pax dei, the “peace of God.”
pontifex maximus: “Greatest priest,” the title adopted by Augustus that made him responsible for overseeing proper cult in the city of Rome. Eventually, the purview of this imperial position extended to the whole empire.
prosōpon (Greek; pl. prosōpa); persona (Latin): Originally indicating the mask worn by actors in Greek theater; the term was adopted by fourth-century Christian theologians to express ideas about the personhood of Christ.
religio: Proper cult to the gods or, after Constantine’s consolidation of the empire in 324, to God. Right religio was seen as necessary for the maintenance of the pax deorum.
schism: From the Greek meaning “to tear,” a division within a single church over some issue of discipline or doctrine.
Septuagint: A collection of Greek translations of Hebrew scriptures completed by the second century BCE.
spectacles: Urban feast days featuring horse races, athletic events, and gladiatorial combats that brought the city together in honor of the presiding gods.
superstitio: Originally referring to extravagant fear of the divine, and often used to characterize foreign (that is, non-Roman) cults; the term comes to mean a religious practice of questionable legitimacy.
Theodosian Code: A compendium of Roman law, compiled between 429 and 438 during the reign of Theodosius II (408–50). Book 16 famously addresses issues having to do with religion, both Christian and non-Christian, within the empire.
Theotokos: “God-bearer,” a title given to Mary that emphasized the high divinity of Christ.
Vandals: A Germanic people who adopted an “Arian” form of Christianity; Vandals took over the Iberian Peninsula and Roman North Africa, ultimately besieging the city of Rome in 455.