Jesus of Nazareth is attested in multiple non-Christian sources from the first and second centuries. These references come from Roman historians, Jewish historians, and even opponents of Christianity — none of whom had any motive to fabricate evidence supporting the Christian movement.
Josephus, a first-century Jewish historian, mentions Jesus twice in his Antiquities of the Jews (c. 93 AD). The shorter reference in Book 20 describes the execution of James as 'the brother of Jesus, who was called Christ.' This passage is almost universally accepted as authentic by scholars. The longer passage, the Testimonium Flavianum in Book 18, contains a description of Jesus as a wise man, miracle worker, teacher, and one who was crucified under Pilate. While the extant text contains likely Christian interpolations, most scholars accept that an authentic core reference existed.
Tacitus, the Roman senator and historian, wrote in his Annals (c. 116 AD) about the Great Fire of Rome and Nero's persecution of Christians. He notes that the movement's founder, 'Christus,' suffered the extreme penalty during the reign of Tiberius at the hands of Pontius Pilatus. Tacitus was hostile to Christianity and had no reason to confirm these facts.
Pliny the Younger, governor of Bithynia, wrote to Emperor Trajan around 112 AD describing how Christians worshipped 'Christus' as a god and met on fixed days to sing hymns. This confirms the rapid spread and worship practices of the early church within 80 years of the crucifixion.
Other sources include Suetonius, Thallus, Mara bar Serapion, and the Babylonian Talmud. Taken together, these sources confirm: Jesus existed, was a Jewish teacher, had followers, was executed under Pontius Pilate during Tiberius' reign, and his followers continued to worship him afterward.