The Christian Coalition for Education (CCFE) has written to headteachers across the country urging them to be careful about what they teach in Relationship and Sex Education (RSE) lessons.
Headed up by former Bishop of Rochester, Michael Nazir-Ali, the coalition in its letter points to guidance issued by the Department for Education last September prohibiting "the promotion of partisan political views in the teaching of any subject in the school", and telling schools to exercise "extreme caution when working with external agencies".
The guidance further states, "Materials which suggest that non-conformity to gender stereotypes should be seen as synonymous with having a different gender identity should not be used and you should not work with external agencies or organisations that produce such materials.
"Teachers should not suggest to a child that their non-compliance with gender stereotypes means that either 'their personality or their body is wrong and in need of changing."
The guidance was issued by the DfE after parents and campaign groups warned about the nature of some RSE resources.
One resource, All About Me, taught young children about masturbation before being withdrawn after the threat of legal action. Another from BBC Teach told children there were over 100 gender identities. After coming under heavy criticism, the BBC made the decision to "retire" the resource.
In its letter, the CCFE urged headteachers to respect the law protecting the right of parents to have their children taught in accordance with their religious or philosophical beliefs, or withdraw their children from teaching that does not do this.
RSE became compulsory in secondary schools, and relationships lessons in primary schools across England last September but implementation was delayed due to the pandemic.
While schools are required under law to consult with parents about the content of RSE lessons, the letter goes on to say that some parent groups and individuals are pursuing legal action against primary schools over lack of consultation and the content of the RSE curriculum or the holding of 'diversity' events "without prior consultation with parents and other stake-holders".
The CCFE said it hoped the letter would remind schools of their duty to fully consult with parents before introducing controversial content.
Bishop Nazir-Ali, coalition's Chair said: "It is heartening to hear that so many schools, and also parents, are waking up to the need for full engagement with what is actually required by the leglisation around RSHE.
"I very much hope headteachers up and down the country will fully understand some of the safeguarding and religious liberty concerns which have arisen since the introduction of the subject."