Christmas is a Christian holiday celebrated on December 25, marking the birth of Jesus Christ, although the actual date of Jesus's birth is debated and may have occurred in the fall. The choice of December 25 is linked to pre-Christian pagan festivals and was formalized by the church in the fourth century, rather than based on biblical instruction. Additionally, traditional Christmas customs, including Santa Claus and tree decorations, have origins in pagan practices and were adopted over time, with no scriptural mandate for their celebration.