Humanists UK has created a new resource called "Assemblies for All" that gives teachers a wide range of ideas for non-religious assemblies and chances to explore topics such as the environment, physical and mental health, arts and culture and LGBT issues.
Under the 1944 Education Act, all state schools in the UK are required to provide an act of daily worship of a "broadly Christian character", but can opt out of it. As of last month, 42 schools have applied to do so.
Graham Nicholls, director of Affinity, a network of more than a thousand evangelical churches told Premier his issue with it: "Well, I can see the purpose of it to try and airbrush out God from the school assemblies that take place," he said.
"There is legislation about there needing to be an act of worship. I can kind of see the fact that it is perhaps a more of a kind of historical antiquated thing that many parents would not think that that was necessary anymore. But it's a real kind of full on assault of having any kind of God content in school assemblies."
Dr Ruth Wareham, education campaigns manager for Humanists UK, told Premier this is not an attack on Christianity, but keeping up with what parents and students want.
"We're not trying to airbrush Christianity out of schools, but it is worth saying that the latest British Social attitude survey found that up to 80 per cent of young people are now non- Christian if you put together those without a religion and those of minority faith," she said.
"What this is seeking to do is redress that balance. So it's simply that these days, a focus on Christianity and a focus on Christian worship, so reverence for a Christian God, simply isn't fit for purpose in our multi faith, multi belief, and multicultural schools."
Dr Wareham added that, "Humanists UK is a champion of inclusive religious education and is happy for Christianity to be talked about in assemblies, but it shouldn't be prioritised over all other religions."
She also said that the current rule on Christian worship is "out of step with public opinion" after a poll commissioned by the Humanists UK found religious worship was the least appropriate of 13 possible different themes or activities that might take place in the assembly.
Listen to Graham Nicholls speaking to Premier's Tola Mbakwe.
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