History and traditions of dating
The early Christians certainly had many arguments as to when it should be celebrated!
Also, the birth of Jesus probably didn't happen in the year 1 but slightly earlier, somewhere between 2 BCE/BC and 7 BCE/BC, possibly in 4 BCE/BC (there isn't a 0 - the years go from 1 BC/BCE to 1! The first recorded date of Christmas being celebrated on December 25th was in 336, during the time of the Roman Emperor Constantine (he was the first Christian Roman Emperor).
It's a time when family and friends come together and remember the good things they have.
People, and especially children, also like Christmas as it's a time when you give and receive presents! No date is given in the Bible, so why do we celebrate it on the 25th December?
The Roman emperor Aurelian created 'Sol Invictus' in 274.Many Orthodox and Coptic Churches still use the Julian Calendar and so celebrate Christmas on the 7th January (which is when December 25th would have been on the Julian calendar).And the Armenian Apostolic Church celebrates it on the 6th January!Most of the world uses the 'Gregorian Calendar' implemented by Pope Gregory XIII in 1582.Before that the 'Roman' or Julian Calendar was used (named after Julius Caesar).