there are many different religions that fall under Christian and they all have slightly different beliefs. butttt the statement in the question is false... almost all Christians celebrate more than one holiday- the most important i think is Easter and Good Friday :) they also have Pentecost and lent which are relevant to some Christians.
Some Christians also celebrate other days like thanksgiving, new years and valentine’s day (it just depends on the person)... although most Christians don’t celebrate halloween since it is seen to promote unholy things and goes against their beliefs! hope that kinda helps :) good luck !!
