The date of Easter is determined according to the lunar calendar, while the date of Christmas is fixed on the solar calendar. Before 325, there was no official celebration of the birth of Christ, and Easter was celebrated by some Christians on Passover (a lunar holiday) and by others the following Sunday. The rationale: Christ’s last supper took place on or around Passover, he was crucified on a Friday, and the festival of Easter celebrates his resurrection two days later.
In 325, church officials at the First Council of Nicaea formalized the date of Easter in an effort to get everyone to celebrate on the same day (and also, possibly, to dissociate it from the Jewish Passover feast). From then on, the holiday was celebrated on the Sunday following the first full moon after March 21, the start of spring.
At the same time, the council inaugurated Christmas by making Dec. 25 the Feast of the Nativity. Because Christmas was not directly related to a lunar holiday, and because it had never been celebrated before—the date of Christ’s birth is not mentioned in the Bible, and questions about it had been settled by a proclamation from the pope just five years earlier—the council was able to establish an unambiguous date for the celebration.
The name of the person we call Jesus was Yeshua. Jesus is the English version of the Greek version of Yeshua.
BTW, its Joshua at the battle of Jericho and Jesus who was born on Christmas because the Old Testament was written in Hebrew and the New Testament was written in Greek. There is no sh sound in Greek, hence Iesous. It was still Iesus in the original King James Bible (1611).
Source for information on name, Brian Palmer – Slate Magazine.