HappyI. I probably won't be all that helpful sorry! I am a strongly believing Christian but I don't get on with all the other Christians and I completely understand the viewpoint that God is a pain in the neck and, moreover, people who push God under your nose are a real pain in the neck. I get problems with extreme (what I would call extreme, I suppose it's subjective) Christian ideas and worry about what people say to children. They will probably drive their children to rebel like mad when they become teenagers depending on the more extreme the religious views and behaviour are. This thing about witches etc is a difficult one. I can't figure out why people are so anti magic in children's books yet there is evidence that some of it is not what Christians should engage with. Definitely King David went to the necromancer woman against God's wishes, so that much is clear. I just think if you live an innocent, loving, clean and decent life, trying to help people and follow the 10 commandments then you are keeping to what God wants. You'll probably break the rules sometimes and have to go back and say sorry and get back onto the right path again. God knows this because he knows we're just human and not perfect. The 10 commandments don't go on about witches though.
Nothing to do with religion but from my psychology background, I do know taking part in deliberate witchcraft can be very dangerous. I would never do that even if I hadn't had my Christian revelation. I became strongly Christian not by going to Church but because I nearly died and had a near death experience. But some people have very bad reactions when they try out any kind of seance or witchcraft type of thing, and because of that I would never touch it. I suppose too I am scared of it, Why play around with something that by its own definition is bad, even if you don't really understand how it can be real? I keep away from it. "Deliver us from evil." Good words!
When I was a Research Psychologist, I helped look into the incidence of Witchcraft and so on in the Harry Potter Books. I was also a qualified Counselling Psychologist and in the Department some Colleagues had referrals from other Hospitals about rare cases of older children having very negative experiences from reading Harry Potter. I loved the books, still do, and my children love them. Anyway, because I was the main Researcher, they asked me to concentrate on just that so we could get results quickly for the sakes of the children. All I found was that there are many names in the books which are used in traditional witchcraft and spells and folk lore about Satan and so on and that some of the spells appear to be similar to spells used in some circles. These are groups which are secret and the knowledge of the spells are meant to be esoteric. However, only a minute number of people were adversely affected by the books and my feeling was that the Enid Blyton books in the 1950s could have frightened and affected a similar proportion of children then, albeit not about witches, but because the stories are frightening and had the power to draw the child right in to the book. The result is that I don't know if witches are actually harmful! People will tell you White Witches are good. It's not my field so I can't say. I do think being too fanatical in a religion can cause anxiety and can reduce the number of social contacts people can make.
I would stay friends. Tell your daughter everybody is different. Try not to offend but say politely that you are not against MLP, but you respect their feelings. It sounds as if you've been very sensible so far and a good friend. If things get very intense and too many activities are sanctioned because of religious scruples, then revise the relationship explaining that you allow your child to play what you believe to be innocent and healthy games, similarly with books.
I truly believe that God loves the children as he showed when Jesus came here. He wouldn't want their games to be complicated by bad witchcraft. I think the effects of the devil/satan are very apparent in the world today and this is working in the devil's favour because people say if God exists why does he allow .... and give examples of terrible things happening to innocent and good people. Dying, I know, is just a matter of leaving this body and going to the beautiful realm where many beings already know you and where it is wonderful. `
I said I didn't expect to be much help - sorry. I'd just hang in there and see how it goes. The very religious friend may need you as a friend at school. She could end up with only her other religious friends for company otherwise. Such strong views are hard to maintain in ordinary life. I dread it when the children get old enough for Harry Potter!! Having to learn about Satanism has ruined the books for me! But they are good stories. Your new friend will definitely ban them though! Good luck there!