is christmas always on the 25th

Not necessarily. Christmas is traditionally observed on December 25th, but the date can vary in different countries and cultures. For example, some Orthodox Christians celebrate Christmas on January 7th, while others celebrate it on January 6th. Additionally, there are some countries that have adopted the Western tradition of celebrating Christmas on December 25th, but they do it according to their own calendar system. So while December 25th is the most common date for Christmas, it's not the only one.