From the perspective of someone who went through faith based schools, in retrospect a lot of what should have been teaching time was given over to religion. For example, in catholic schools, preparing pupils for First Holy Communion and then Confirmation a year or so later, both rites of passage. This entailed learning and then parroting the catechism, a complete waste of time and no use to man nor beast, unlike the useful parroting of times tables a useful tool to take through life. Faith schools are there for what parents believe in, a child can't make an informed choice and therefore a large part of it is brainwashing. Richard Dawkins in his God Delusion book cited catholicism and Islam the worst examples of that. I'm inclined to agree although my thoughts are also religion is even more deeply ingrained with the latter. I can't imagine amongst my peer group ever wanting a prayer room, having to attend masses during school time was more than enough! I'm not entirely against religious schools, I sent my children to a CofE junior school, where there was altogether a much lighter touch. I also think it's a good thing to be taught about comparative religions and the way they are sometimes a lynch pin in different societies, but again, a dispassionate approach needs to be adopted, because as we well know, religion in many instances is not always a force for good and have many downsides.
I think Katherine Birbalsingh appears to have the interests of her pupils at heart and also seems to be doing much to raise standards. I think there is a need for secularism in schools and not making adherents to any particular religion a special case..