why does russia celebrate christmas in january

Russia has a unique calendar system that is based on the Julian calendar, which is 13 days behind the Gregorian calendar used in most of the world. This means that Christmas in Russia falls on January 7th instead of December 25th. The celebration of Christmas in Russia dates back to the early days of Christianity, and the holiday has been celebrated since the 10th century. It is a time of joy and celebration, with many traditions and customs that are unique to Russia.