Okay so it isn't just me. That's something I haven't understood. I recall a fair amount of sorcery and the like in the Narnia series . . .
When Eustace and Jill are being persecuted by the school bullies in The Silver Chair (just about the only appearance of a school in the Narnia books - and Lewis takes his shots in asides to the grownups) they decide to ask Aslan to let them go into Narnia. Jill asks Eustace if he means to draw circles on the ground and recite spells and stuff . . . and Eustace answers that he doesn't think Aslan would like that very much.
And there's a great scene in Prince Caspian where Dionysus/Bacchus and his wild Maenads make an appearance -- pagan riot at its most anarchic and dangerous. But Aslan has summoned them and has dominion over them. Susan remarks to Lucy that she "wouldn't feel safe with Bacchus and his wild girls if Aslan wasn't with us."
Which comports with Lewis's philosophical view that the pre-Christian world contained hints and foreshadowings of Christ and Redemption . . . neat stuff.