Salam
"The supposed date of the birth of Jesus being the 25th December has long been suspected to be inaccurate; which is true, since it was at a much later date when Christians began to celebrate the birth of Jesus, and no reference of such a festival is made in the Bible. Numerous theories have been put forward of how and why the 25th December was chosen. The 25th December was the birth of the Roman Pagan god Mithras: the Roman Catholic writer, Mario Righetti, writes that it was to facilitate and aid the bringing in of the pagan masses to the Roman Church, as the latter found it convenient to merge the pagan festivals and link it to the birth of Christ (Manual of Liturgical History, 1955, Vol. 2, p.67).
Furthermore, since there is no reference of Jesus birth in the Bible, early in the churchs establishment, numerous dates were proposed to have been the date of his birth. At around 200 CE, Clement of Alexandria complained that certain Egyptian theologians over curiously assigned, not the year alone, but the day of Christs birth, placing it on 25 Pachon (20 May) in the twenty-eighth year of Augustus (Stromata I.21) In Cyprus, at the end of the fourth century, Epiphanius asserts that Christ was born on 6 January (Hear li 16, 24 in P.G., XLI, 919, 931). Around the same time, Chrysostom preached an important sermon in 386 CE, in which he tried to unite Antioch in celebrating Christs birth on 25 December, part of the community having already kept it on that day for at least ten years.
Thus a certain evolutionary theme can be seen, where the dates of Jesus birth varied a great deal. The Holy Quran is more specific than the gospel accounts in stating that the birth of Jesus was most likely to be in the summer:
And the pains of child-birth drove her (Mary) to a trunk of a palm tree. She said; "Would that I had died before this and been forgotten and out of sight!" Then cried out to her from below her; "Do not grieve, your Lord has placed under you a stream. And shake towards yourself the trunk of the palm tree, it will let fall upon you fresh ripe dates. (19: 23-25). The fact that ripe dates do not grow in the middle of winter, but rather during the summer months points to the birth date being in the summer months. This is probably historically more accurate, as later in Luke shepherds were camping outside in the country while watching their sheep, which would have been less likely to have happened in winter when it would get very cold outside."
http://muslimcommentaryofbible.wordpress.com/contents-of-a-muslims-commentary-of-the-bible/10-the-birth-of-jesus/Syed
