Well my DS’s school calls it Life and Morality not RE, but when asked they confirmed it was just religion and no philosophy.
I would think that given say Platonism ‘s (esp later Platonisms) influence on the doctrines of all the Abrahamic faiths it would be useful to learn about this common theme, surely it’s best to teach about common denominators?
Or is there something objectionable in learning about the actual development of religion? To this end, schools very rarely (if ever) touch upon the very early church and the impact of politics on what then becomes the orthodox view. Surely a school should be equipping children with critical analysis skills.