When was Jesus actually born?
December 25th seems an unlikely date. The church chose that date because the pagan festival of Saturnalia was celebrated then. The church wanted to replace the pagan festivals with Christian celebrations.
It seems that modern scholarship believes Jesus was born in September or October between the years 6 B.C.E. (Before the Common Era) and 1 A.D. (Anno Domini—year of our Lord). The shepherds would be in the fields at that time, and it would be 6 months after John the Baptist was born. John, it is calculated, was born in March.
As far as my research can go, the year depends on the date of Herod the Great’s death and whether it was a full or partial eclipse to which Josephus refers. (Josephus is a first century historian.) It gets so involved that I am confused.