The historicity of Jesus concerns the degree to which sources show Jesus of Nazareth existed as a historical figure. It concerns the issue of "what really happened", based upon the context of the time and place, and also the issue of how modern observers can come to know "what really happened". A second issue is closely tied to historical research practices and methodologies for analyzing the reliability of primary sources and other historical evidence. It also considers the question of whether he was a Nazirite.
Virtually all New Testament scholars and Near East historians, applying the standard criteria of historical investigation, find that the historicity of Jesus is effectively certain although they differ about the beliefs and teachings of Jesus as well as the accuracy of the details of his life that have been described in the gospels. While scholars have criticized Jesus scholarship for religious bias and lack of methodological soundness, with very few exceptions such critics generally do support the historicity of Jesus and reject the Christ myth theory that Jesus never existed.
The historicity of Jesus is distinct from the related study of the historical Jesus, which refers to scholarly reconstructions of the life of Jesus, based primarily on critical analysis of the gospel texts. Historicity, by contrast as a subject of study different from history proper, is concerned with two different fundamental issues. Firstly, it is concerned with the systemic processes of social change, and, secondly, the social context and intentions of the authors of the sources by which we can establish the truth of historical events, separating mythic accounts from factual circumstances.
All extant sources that mention Jesus were written after his death. The Christian Testament represents sources that have become canonical for Christianity, and there are many apocryphal texts that are examples of the wide variety of writings in the first centuries AD that are related to Jesus. Many scholars have questioned the authenticity and reliability of these sources, and few events that are mentioned in the gospels are universally accepted.