why is christmas december 25th

It's believed that Christmas was celebrated on December 25th because it was the day when the Roman Empire adopted Christianity as its official religion. Some historians believe that the early Christians chose this date to commemorate the birth of Jesus, but it's also possible that they chose it because it was a time of year when people were more likely to be able to travel and gather together for religious observances. Whatever the reason, December 25th has been the traditional date for celebrating Christmas ever since.