Jesus also referred to as Jesus of Nazareth and Jesus Christ. He is the central figure of Christianity. Most Christians believe him to be the incarnation of God the Son and the awaited Messiah (Christ) prophesied in the Old Testament. His birth is celebrated annually on December 25 (or various dates in January for some eastern churches) as a holiday known as Christmas his crucifixion is honored on Good Friday and his resurrection is celebrated on Easter. The widely used calendar era "AD" from the Latin anno Domini ("in the year of the Lord") and the alternative "CE" is based on the approximate birth date of Jesus.