one only need to research Jewish, Greek and Roman history to realise that Jesus existed as a single person and whom was quite notorious.
The historical Jesus is Jesus of Nazareth as reconstructed by historians using historical methods. These methods do not include theological or religious axioms, such as biblical infallibility. Though the reconstructions vary, they generally agree on these basic points: Jesus was a Jewish teacher who attracted a small following of Galileans and, after a period of ministry, was crucified by the Romans in Palestine during the governorship of Pontius Pilate. The quest for the historical Jesus began with the work of Hermann Samuel Reimarus.
Historians have developed a number of methods to critically analyze historical sources:
Criterion of dissimilarity. (More narrowly, the criterion of embarrassment.) Statements contrary or dissimilar to the author's agenda are likely to be more reliable. For example, a Christian source would be unlikely to claim that Jesus was from Nazareth (rather than from Bethlehem), unless his family was actually from Nazareth, as this was a cause of embarrassment.
Criterion of multiple attestation. When two or more independent sources present similar or consistent accounts, it is at least certain that the tradition predates the sources. See the Historicity of Jesus for an example of the multiple independent attestations of the fact that Jesus was a real person.
Contextual and linguistic criteria. A source is more credible when the tradition makes sense in the context of what historians know about the cultural background. There are some interesting conclusions that can be drawn from linguistic analysis of the gospels. For example, if a dialogue only works in Greek (the language of its written source), it is quite likely the author is reporting something at least slightly different from the original.
Author's Agenda. This criterion is the flip side of the criterion of dissimilarity. When material serves the perceived purposes of the author or redactor, it is suspect.For example, various sections of the gospels, such as the Massacre of the Innocents, portray Jesus' life as fulfilling prophecy, and in the view of many scholars, reflect the agenda of the gospel authors rather than historical events.
Historians have little other than Christian accounts on which to base a biography of Jesus. Greek accounts portray Jesus as the son of adultery, and Jewish accounts portray him as a magician, but these accounts tell us virtually nothing about Jesus as a historical figure but they do tell us that he existed.
According to the Gospels and other early sources, Jesus was active in Galilee and Judea (modern day Israel, Palestine, and Jordan) during the first half of the first century. Following the break-down of earlier Jewish kingdoms the partially-Hellenized territory was under Roman imperial rule, but there were ongoing hopes of a revival of sovereignty. The Roman Prefect’s first duty to Rome was to maintain order, but although the land was mostly peaceful, there was an ongoing risk of rebellion, riots, banditry, and violent resistance. Four decades after Jesus’ death the tensions caused by Jewish hopes for a restoration of the kingdom of David culminated in the first Jewish-Roman War and the destruction of the Temple in Jerusalem, which in turn catalysed the final break between Christianity and Rabbinic Judaism.
Given the historical context in which the Gospels took their final form and during which Christianity first emerged, historians have struggled to understand Jesus' ministry in terms of what is known about first century Judaism. According to scholars such as Geza Vermes and E.P. Sanders, Jesus seems not to have belonged to any particular party or movement; Jesus was eclectic (and perhaps unique) in combining elements of many of these different – and for most Jews, opposing – positions. Most critical scholars see Jesus as healing people and performing miracles in the prophetic tradition of the Galilee, and preaching God's desire for justice and righteousness in the prophetic tradition of Judea. (According to Geza Vermes, the fact that Jesus' followers addressed him as "lord" indicates that they likened him to notable miracle workers and scribes. see Names and titles of Jesus)
Nevertheless, Jesus reflects the cultural milieu of his time. Many of his teachings echo the beliefs of the Qumran community (which was probably a branch of the Essenes) and of some of the Pharisees. In Jesus' day, the two main schools of thought among the Pharisees were the House of Hillel and the House of Shammai; the accusations of hypocrisy which Jesus is reported as levelling at Pharisees in general may have been directed against the stricter members of the House of Shammai, although he also agreed with their teachings on divorce (Mark 10:1-12). In general, Jesus' Sermon on the Mount is stricter than the teachings of the House of Hillel.
Finally, Jesus' repeated declarations that the kingdom of God was at hand echoed popular apocalyptic views and the political views of the Zealots. Following the failure of the Maccabean insurrection against the Seleucids almost two centuries previously, most Jews of Jesus' time believed that the restoration of the kingdom would be accomplished by God, not by any movement of Jews. However, he did believe that this restoration was imminent. Jesus was enigmatic at best about his claim to actually be the presumptive monarch. That he speaks of twelve disciples is probably symbolic of the twelve tribes of Israel, and thus a metaphor for "all Israel". According to Geza Vermes and others, the use of the terms "messiah" and "son of God" by Jesus' followers indicate that they believed he would assume the monarchy upon the restoration of the kingdom (see Names and titles of Jesus).