The origin of Christianity seems obvious: since Christ (Χριστός; Christós) is the basis for the term, Christianity must have originated with Christ – the Greek version of the Hebrew title “Messiah” (משׁיח; mashiach), meaning “anointed one.” However, Jesus never refers to Christianity, nor do his first followers use the word to describe their movement. In fact, “Christianity” never appears in the pages of the New Testament. Instead, only those outside the movement describe the first followers of Yeshua as “Christians.” The New Testament writers understood themselves as part of Jewish religious expression and history, rather than starting a new religion called Christianity.
While “Christianity” does not feature in the New Testament, the title “Christian” (Χριστιανός; Christianós) appears three times. When it does, it is never a self-designation; rather, “Christian” is a name that comes from outside the Jesus assembly. For example, Acts notes in passing that “the disciples were called ‘Christians’ (Χριστιανούς) first in Antioch” (11:26). Luke does not say that the disciples called themselves Christians, but that they “were called Christians” by others. Similarly, the Herodian king Agrippa asks Paul, “Are you so quickly persuading me to become a Christian?” (Acts 26:28). “Christian” was also used as a term of derision, but the New Testament urges Jesus-followers not be discouraged if they’re called by this name: “If anyone [suffers] as a ‘Christian,’ let them not be ashamed, but glorify God because of [this name]” (1 Pet 4:16). Although some believers in Yeshua were disparaged as “Christians,” this verse turns the title into one of glorification. Still, 1 Peter encourages believers to make the best of a title they did not invent; the nascent Jesus movement located itself within the religion of Israel, not as a Christian innovation apart from Jewish worship or tradition.
The Romans also provide examples of “Christians” being used by those with unfavorable views of the group. The ancient historian Tacitus writes about “a class of people, despised for their vices, whom the crowd called ‘Christians’ (Christianos). Christus, the founder of the name, had undergone the death penalty during the reign of Tiberias, by the sentence of the procurator Pontius Pilate, and the pernicious superstition was checked for a moment, only the break out once more, not merely in Judea, the home of the disease, but in the capital [of Rome] itself, where all the horrible and shameful things in the world gather” (Annals 15.44). Tacitus explicates that to which 1 Peter alludes; namely, that non-believers used “Christian” as a title of derision against a despised religious movement.
According to our extant literature, “Christianity” originates in the writing of Ignatius (c. 100 CE). Unlike the derisive uses of “Christian,” Ignatius uses “Christianity” as a positive term in opposition to Judaism. The Gentile Ignatius asserts, “It is absurd to profess Christ Jesus and to live as the Jews. For Christianity (Χριστιανισμός; Christianismós) did not embrace Judaism, but Judaism [embraced] Christianity” (Epistle to the Magnesians 10). Ignatius argues that practitioners of Judaism (i.e., Jesus’ earliest followers) “embraced” a new religion called “Christianity,” thus Christians should not practice Judaism. The church father’s view of history is imprecise; the New Testament does not suggest that Jesus’ Jewish followers either abandoned Judaism or adopted an alternative religion called “Christianity.” To the contrary, the divide between what, today, we call “Judaism” and “Christianity” only began to emerge in the generations after Jesus and his Jewish apostles.