What a piece of work is a man. How noble in reason, how infinite in faculties, in form and moving how express and admirable, in action how like an Angel, in apprehension how like a god, the beauty of the world! the paragon of animals – and yet to me, what is this quintessence of dust? Man delights not me – nor Woman neither, though by your smiling you seem to say so.”
Hamlet Act 3, scene 1, 55–87
Once upon a time there was God and His Creation.
But God was BORED. All he got all the time from his ungrateful Creation were prayers asking for stuff with never quite enough thank you prayers. His Creation were a very disappointing lot indeed.
Since He was omnipotent and omniscient, He always knew the Future and remembered everything. Because God was all-wise, nothing ever surprised Him and, boy, was it BORING.
Indeed, one day He got so bored that He thought He would commit suicide. No one would notice anyway. The ones who always denied He existed would never have acknowledge His existence whether He lived or died. The ones who believed in Him would carry on believing in Him whether He was dead or alive. The ones who were agnostic just wouldn't care either way. It really made no difference at all.
But fortunately for God, He remembered just in time that He was omnipotent and could think of a way of amusing Himself without quite killing Himself.
And it was this.
He turned Himself into all of His Creation, but, having divided Himself up into an infinite number of souls and things, He lost the completeness of His former omniscience. While the knowledge was still there, somewhere, scattered and spread out, it was flickering and blinking and flashing at very irregular intervals rather than shining strong as it used to do when He was completely in charge as a Singularity.
But this was the WHOLE IDEA. God, by dividing Himself up into all of His Creation remained with His Creation, but kept the element of forgetfulness as to what was around the corner. When it happened, there were always quite a few people who would say, "I just knew that was going to happen anyway!", and they are sort of right when they say that, for wisdom enables you to foretell the future.
To help Himself remember important things when He really needed to, God would stick helpful notes in places like people suffering from Alzheimer's putting post-it notes around in their home to remind them to do important things, in the form of Holy Books, with various tribes and nations in different parts of the world. Sadly, there was never enough people who would read them properly, or interpret the messages and commands sensibly and implement His instructions wisely, for long enough, before slipping into cruelty, chaos, forgetfulness and madness.
By turning Himself into humanity God had given Himself the forgetfulness with which to make life seem fresh, full of danger and adventure again, for eternity is a very long time indeed.