When was Christmas first celebrated?   In an old list of Roman bishops who conducted mass complied in 354 A.D., these words appear for the year 336 A.D. – “25 Decem natus Christus in Betleem Judeae.” – “December 25, Christ born in Bethlehem, Judea.:  This day, December 25, 336 A.D., is the first recorded celebration of Christ’s mass in recognition of his birth.