Saint Julius, also known as Pope Julius I, was a significant figure in early Christianity, serving as the pope from 337 to 352 AD. He is best known for his role in establishing the date of Christmas, which is celebrated on December 25. Julius I also worked to promote the authority of the papacy and defend the faith against various heresies of his time. During his papacy, Saint Julius supported the development of church structures and the establishment of church councils. He is remembered for his efforts to maintain unity within the Christian community and for his contributions to the growth of the early Christian Church. His feast day is celebrated on April 12.