Religion, or lack if it, is not important. Individual children are discriminated against because they have a different religion or no religion from the religion practiced in a local school.
Discrimination in schools should be abhorred.
Schools that accept funding from the state in any form should not be allowed to selected pupils based on their religion. It is a gross attack on liberty for a school to consider whether or not a child is christened or not to be relevnat to their selection to a particular school.