Joseph A. Fitzmyer – Professor Emeritus of Biblical Studies at the Catholic University of America, member of the Pontifical Biblical Commission, and former president of the Catholic Biblical Association – writing in the Catholic Church’s official commentary on the New Testament, writes about the date of Jesus’ birth, “Though the year [of Jesus birth is not reckoned with certainty, the birth did not occur in AD 1. The Christian era, supposed to have its starting point in the year of Jesus birth, is based on a miscalculation introduced ca. 533 by Dionysius Exiguus.”
Roman pagans first introduced the holiday of Saturnalia, a week long period of lawlessness celebrated between December 17-25. During this period, Roman courts were closed, and Roman law dictated that no one could be punished for damaging property or injuring people during the weeklong celebration. The festival began when Roman authorities chose “an enemy of the Roman people” to represent the “Lord of Misrule.” Each Roman community selected a victim whom they forced to indulge in food and other physical pleasures throughout the week. At the festival’s conclusion, December 25th, Roman authorities believed they were destroying the forces of darkness by brutally murdering this innocent man or woman.
In the 4th century CE, Christianity imported the Saturnalia festival hoping to take the pagan masses in with it. Christian leaders succeeded in converting to Christianity large numbers of pagans by promising them that they could continue to celebrate the Saturnalia as Christians.