Daemonism is the study on daemons, daemians, and anything related to daemons.
Is is a cult/religion?
NO. It is very much not a cult or religion. It's a philosophy, an idea. People can enjoy whichever religion they choose to have, and still have a daemon. Daemonism, despite a similar name, has nothing to do with demons, which are very very different indeed.
Are you weird psychos?
Daemonism is not in any way associated with DID. People consciously choose to construct a daemon, and both human and daemon know that they are just two halves of the same person.
But you're crazy! Philip Pullman didn't mean daemons were real in the books!
This is often something I hear from non-daemians, however they misunderstand. Pullman popularised daemonism, but did not invent it. In fact, greek philosophers (like Socrates) were believed to have daemons. And also Carl Jung explained the idea of "headmates" and "imaginary friends" in the 1800s, long before Philip Pullman was even born.
Daemonism is very much real to daemians yes. Not physically real, but mentally real. We love our daemons and our daemons love us in return.