Two primary schools in Dublin have warned parents they will not be able to celebrate Christmas if there is a change of patronage.
It comes as one of eight Catholic primary schools in the Portmarnock-Malahide-Kinsealy area is to transfer to a non-denominational model.
Two of the schools have written to parents claiming that Christmas, Easter and St Patrick's Day would no longer be marked.
One of the schools also told parents that a large number of teachers would consider leaving if there was a change in patronage.
Parents will be asked to vote on whether or not they want their child's school to change from a religious ethos or not.
In a statement, Educate Together said students at their multi-denominational/equality-based schools are "exposed to different beliefs and perspectives in a respectful way that encourages critical thinking".
"Christmas is, of course, marked in Educate Together schools nationwide; just as our schools endeavour mark Diwali, Eid, Vaisakhi and other religious festivals throughout the school term," they added.
CEO of Educate Together Paul Rowe says their model celebrates the identity of all students.
"Educate Together schools are based on an equality principle in which the identity of all children are guaranteed equal respect," he said.
"That means the schools mark all kinds of celebrations, religious and non-religious cultural events in an appropriate way."