– Ireland’s state-run secondary schools can no longer assume that their students will receive religious instruction, the government has said, directing the schools to offer alternative classes — a striking move in a country where education has long been dominated by the Roman Catholic Church.

Irish law already states that government-run schools cannot require students to take religion classes, which have been dominated by Christian doctrine. But that law has had limited effect, as schools have routinely enrolled all students in the courses unless their parents opted them out.

The schools have not usually offered alternative classes, often requiring that exempted students remain in their classrooms during religion courses that they were, in theory, not taking. This week, the Department of Education directed state-run secondary schools to end the opt-out requirement — so that taking a religion class would be an affirmative choice, not a default — and to offer other courses that could be taken instead.

And on Wednesday, the Teachers’ Union of Ireland called for the change to apply to all secondary schools in the country, including religious ones.

“It may have been reasonable when these schools were originally established for a school to assume that its pupil population was predominantly Catholic and to arrange religious instruction accordingly,” the Department of Education said. “In a changing context, the constitutional right not to attend religious instruction must be given effect through changed practices.”