Circa 336, March
Pope Julius I, declared December 25th as the official date for the celebration of the Nativity. The decision was likely aimed to align the Christian celebration with existing Roman winter solstice festivals, such as Saturnalia, and Sol Invictus . The proclamation is believed to have been done c. March, 336
The proclamation served to establish a uniform feast day for the Western Church. Before this, Christian celebrations of Christ's birth did not have a universal date, with many easterners celebrating on January 6th. Some historians believe the date was chosen because it was precisely nine months after March 25th, the date commonly believed by early Christians to be both the conception of Jesus and the anniversary of his death.There is no mention of the date of Jesus' birth in the Bible. The existence of shepherds with their flocks in the fields at night suggests a time of milder weather, which points away from December. Many historians believe that Jesus was born between 7 and 2 B.C. and that December 25th was not the actual date of his birth.
