"Based on the
biblical passages that record the nativity story and related
events, many scholars reject December 25 as the date when Jesus Christ
was born. The Bible appears to indicate that Jesus was most likely
born in late September; however, December 25 has become so
entrenched as Christmas Day that it will likely never change."
- Date of the Birth of Jesus Christ, by
Ronald G Falconberry,
(http://biblestudies.suite101.com/article.cfm/the_birth_of_jesus)
“And, as these shepherds
had not yet brought home their flocks [when Christ was
born in Bethlehem], it is a presumptive argument that October had
not yet commenced, and that, consequently, our Lord was not born
on the 25th of December, when no flocks were out in the fields; nor
could He have been born later than September, as the flocks were
still in the fields by night. On this very ground the nativity in December
should be given up. The feeding of the flocks by night in the fields is
a chronological fact . . . See the quotations from the Talmudists in
Lightfoot.”
- Adam Clarke, Commentary, Vol. 5, p. 370.