Probably the stars had dæmons just as humans did, and experimental theology involved talking to them. OMG, I remember reading a science fiction novel ca 1971 that had something of this concept in it. Remember little of it now.
The Perelandra trilogy has exactly this concept. It's really central to the plot, I think. The oyarsa (sp?) are the daemons of the various planets.
Pullman is just a hateful atheist, who set out to trash Lewis's Narnia books. Too bad he can string words together. But he has a long way to go before he has Lewis's persuasive facility with the language; you don't pick that up by the side of the road.
If he were as good as Lewis, his hatred wouldn't be so obvious. I still remember when I read The Last Battle for the first time, at the age of 7, being completely surprised by the line, "And then he no longer looked to them like a lion. . . . " Lewis doesn't wear his heart on his sleeve in his fiction.
I have read Perelandra several times, but not recently. I just don’t remember stars in it having demons. I can see why kids would like to read Pullman because they are more exciting to read—at least the first two of the triology. Third is boring. But Lewis’ writing stays with you and informs you throughout your life. At least it does me. I’ve read That Hideous Strength many times. I’ve thought about it a lot through the years. I enjoyed reading Pullman, and promptly forgot the details. It’s a one-time, forgettable book.