Let's look at reality first and see if this gives us an insight into what this devil, satan business is about.
This is hard for the fundamentalist Christian because they have Special Creation which makes any kind of sensible conversation difficult, but you're not like that, so.
Life began as some single event, RNA became a single celled organism and that organism produced every living thing on planet earth, including us. None of this was an accident, it is Creation. Humans were always destined to arise from evolution. Firstly there was a need for processes to produce soils, then forests to produce coal which was for the industrial revolution. All the coal was laid down pretty much at the same time before organisms had evolved to break it down into basically dirt.
Then we needed plants to evolve so could eventually feed the masses and so on. Then humans begin to form in the natural systems. Primitive forms of us were just another animal in the food chain. When we arrived at our present form we had within us all the cunning and self-first instincts of an animal. Animals kill each other, steal each other burrows, nests, etc. They steal each others food. Humans even today have all these instincts bubbling below the surface and scripture describes this animal aspect of the human as the devil, satan, etc.
The other aspect of being human is that we have attached to our being and aspect, an essence of God Himself, so humans are in conflict between the animal nature and the spiritual nature.
As for God foreknowing. God is eternal, therefore there is now linear progression of time, God is not subject to time so everything that will happen has happened but we must travel the journey of time and try to overcome our animal nature, the satan that is inside us, the corrupt ego.
Oh the mystery indeed.
