You have to be clear on what you are doing and what you are not doing. You are creating a delusion, you are not creating anything concrete. If I think of a hippopotamus, it doesn't matter how long I think of one, I will never create a real hippopotamus - it will always be part of my imagination, part of my mind, somewhere in my brain.
A god, a pixie, a tulpa, a dead relative, and invisible friends who talk to you are not real but they are all the same mental phenomenon.
When people suffer serious mental illness, it appears that the neural pathways become misconnected. Imagine you flick the light switch on but the radio comes on instead. So you turn the radio off and the TV starts. Obviously, you think the wiring is at fault. However, let’s say that you open the door and it is night but through the window it is broad daylight. A voice that seems to be in your head tells you to lick the floor – it keeps saying this; it doesn’t stop. You stare at the picture on the wall. The people in the picture are staring back. They are trying to tell you how to stop the voices, but you can’t hear them properly. Suddenly the world is very confusing but, to you, this is your reality. You become worried. You tell someone, they think you're mad. The lights, radio, TV all work and it is daylight. But humans perceive only what the brain tells them that they are perceiving: if it goes wrong then your reality is not anyone else’s reality.
Reality arrives via a healthy brain and is more or less the same for everyone. You can alter it with drugs, like LSD. The neural pathways become disrupted, imagination and reality combine, but the brain, now confused, does not see the same reality as anyone else but to the person who took the drug, it is reality: things that happen can be funny, amazing, or horrible – but they are real.
Now… do you know what “sentient” means? Here’s what the Oxford English Dictionary says:
Adjective: That feels or is capable of feeling; having the power or function of sensation or of perception by the senses.
Now, in broad terms, to be sentient, as a minimum you have to have a physical body that will respond to stimuli. More usually, you have to have some sort of nervous system and that requires a brain as well as a body. A god, a pixie, a tulpa, a dead relative, and invisible friends who talk to you cannot have a body or a brain, at least not an independent one. So your mind trains itself to have two personalities: there is you, and then there is a god, a pixie, a tulpa, a dead relative, and invisible friends. You treat this personality as if it were another person (although you know it cannot be). The neural pathways form more strongly and the connection is made so that the voices in the head appear.
When the neural pathways become well-established, you may find that the voice in your head will start talking as if it were just another human. It will not be able to know any more than you know; it will not be able to do maths or art better than you, in fact, it will be limited by your own mind - this is how we know that gods are imaginary - they never come up with things we could not have thought of - no god ever invented a cure for anything and no god ever made a scientific discovery... this is because they are limited by the brain of the person who invents them.
There are cases that you will have heard of where gods speak to people, where dead relatives also speak. These people have simply deluded themselves and trained (unconsciously) their neural pathways – for them, it is reality, they think they hear voices and sometimes see these people. But it is a delusion.
What do you think? Is it a good idea to create a delusion?