Glad you asked! If I were God I would tell you! There are many ways scholars interpret the estimated date of Jesus birth! From Biblical and historical events and astrological events during the time of his birth. For example the reign of King Herod the Great. The date of the decree for taxation made by Caesar. Even to the type of sheep grazed and birthing at that time and their birthing times according to history. The methods are various but they all zero in on a accurate time frame of when Jesus was born! The priestly order of Zachariah and his time of priestly administration in the Temple is another way to cross check this date! I will give you one method among many methods that are used! If I do not use just one method we will end up publishing a book on this subject! According to Luke Chapter 3 Jesus began his ministry when he was thirty years old. Jesus began preaching after being baptized by John the Baptist. Based upon Luke’s Gospel John began baptizing people in the 15th year of the reign of Tiberius Caesar or about A.D. 28-29. By working backwards Jesus was probably born no later than 1 B.C. Herod the Great died after the January eclipse of 1 B.C. or even 1 A.D. after the eclipse that occurred in December of 1 B.C. Bottom line is all the methods combined put Jesus birth in the 6 to 4 B.C. range in history. Merry Christmas! James & Hamsa Sasse. GodWhoisGod.com