First, the nearly 2,000-year existence of Christianity, which has undeniably been a significant part of world history for the last two millennia, must be recognized as valid testimony to the existence of Jesus. Next, the main written historical accounts of Jesus are found in the New Testament, primarily the Gospels. The Catechism of the Catholic Church affirms,
The Church holds firmly that the four Gospels, whose historicity she unhesitatingly affirms, faithfully hand on what Jesus, the Son of God, while he lived among men, really did and taught for their eternal salvation, until the day when he was taken up. (CCC 126)
Additionally, many ancient secular writers such as Josephus and Pliny the Younger left evidence of Jesus’ existence.