The chief inspector of England's schools has suggested dropping their legal obligation to provide "a daily act of collective worship".
The legal duty of daily worship is widely not observed in schools
David Bell, the head of Ofsted, said 76% of secondary schools were breaking the law in not doing this.
Mr Bell said perhaps the requirement should now be weekly or even monthly, rather than daily.
His comments marked the 60th anniversary of the Education Act which introduced the worship requirement.
He said that when the 1944 Act was passed, "spiritual development was probably considered to be synonymous with the daily act of Christian worship".
"But, with the broadening of Britain's religious and cultural identity, spirituality has come into its own as encapsulating those very qualities that make us human."
During school inspections, otherwise excellent governing bodies were downgraded because they did not meet the requirement.
So he had taken "a pragmatic stance based on intent and action", but "weighty questions" remained.
"What, as a society, do we think about collective worship in non-denominational state schools?"
The 1988 Education Reform Act added that the collective worship should be "wholly, or mainly, of a broadly Christian character".
Confusingly, though, later official guidance said not all worship need be "broadly Christian".
How many people, apart from schoolchildren, were required to attend daily worship, Mr Bell asked.
"Are we right to be requiring from our young people levels of observance that are not matched even by the Christian faithful?"
Mr Bell applauded the Commission for Racial Equality chairman, Trevor Phillips, for his comments about the problems associated with multiculturalism and the need to foster a sense of Britishness.
"Would we weaken that strengthening of 'Britishness' if we no longer required children and young people to worship daily in the Christian tradition which is so bound up with our history and heritage?" he said.
It would encourage those who participated to do so "in a more meaningful way".
"So, perhaps consideration should now be given to making the requirement for collective worship weekly, or even monthly, rather than daily," he said.
It might be time to "leave more room to schools in determining what that worship should involve".
The Department for Education and Skills said ministers' priority was the move towards a national framework for religious education, being led by the Qualifications and Curriculum Authority.
"We know that Ofsted have identified good examples of schools that use collective worship effectively to reinforce pupils' spiritual, moral, social and cultural development, and we encourage all schools to follow this lead," a spokesperson said.
A spokesman for the Church of England said it would be concerned about any change.
A great deal of good worship was going on even if not everyone complied with the law.
If the requirement were reduced, the risk was that in some places "observance would fall to zero".
It would be better to produce better guidance, once the discussions about an RE syllabus had been concluded.
The general secretary of the Secondary Heads Association, John Dunford, said he was pleased someone had recognised that compulsory collective worship was "a contradiction in terms".
"We strongly support the chief inspector's call for abolition in the knowledge that schools will continue to take very seriously their responsibility for the spiritual development of young people."
"David Bell is saying what sensible people in education have been saying for years," said Marilyn Mason of the British Humanist Association.
"His opening up of the debate is very welcome, though he seems largely to have forgotten that many, perhaps most, school pupils are not religious at all - they don't want to worship even once a month."