I refer you to my other thread inspired by the exclusion of consideration of non religious world views from discussion in a cross party committee on RE.
I am in two minds over that at the moment. One is why should non religion appear in RE, the other is that world views should be taught in RE. From my POV British humanism is not immune from cultural imperialism or politically engineering the elimination of religion in the same way that all majorities aren't.
I suspect you are over-thinking it, Vlad.
After all if the aim is to review theism in historical, philosophical, cultural, social, legal and political terms then since you'd have to note that not all theists ascribe to the same religion (noting the differences between religions) then why wouldn't you also note that some people were atheists?