It seems apparent that Mr. O'Brien sees the religious allegory in Potter's life, but then chastises the author for not admitting "some kind of higher power". It's likely that O'Brien would have accused Rowling of blasphemy had she done so.
You can't win with critics like this who are so obsessed with their narrow view that they see a nefarious purpose in anything that does not track exactly with their preconceptions..
I believe if Rowling were a professed Christian like Tolkien and Lewis, the Potter series would be applauded for its insightful and vivid portrayal of the battle between good and evil, yadda,yadda,yadda. The writings of Tolkien and Lewis are as fanciful and as full of magic, mystery and alternate worlds as the writings of Rowling. But that’s okay because they’re Christian.
Too much time, effort and ink has been wasted by Christians lambasting poor fictional Harry instead of focusing on real evil in the world.