Jesus was a Jew.
He was born to a Jewish mother in Galilee, a Jewish region. His life, teachings, and ministry were all rooted in Jewish tradition and law. All of his followers, disciples, and associates were also Jewish. He observed Jewish holidays, worshiped in synagogues, and frequently quoted from the Hebrew scriptures (the Tanakh, known as the Old Testament in Christianity). He sought to reform and revitalize Judaism, not to create a new religion. While Christian theology eventually developed around the belief that Jesus was the Messiah and the Son of God, his own religious identity was firmly Jewish.