Jesus wasn't actually born on December 25. Since no one knows Jesus' true birthday, December 25 was chosen to commemorate the day Jesus was born. It is not known for certain why early Christians...
No, Jesus was actually born on the 15th of the Jewish month of Tishri. That is somewhere in September-October. Dec 25 is a Pagan Holiday of Yule but Christians didn't want it to be celebrated so...