Is the Devil unable, but willing to prevent good? Then he is incompetant.
Is the Devil able, but unwilling to prevent good? Then he is benevolent
Is the Devil both able and willing to prevent good? Then from where cometh good?
Is the Devil neither able nor willing? Then why call him "Devil"? — IvoryBlackBishop
There are Devils in many religions (Squanto was the name given to Squanto after he changed his name in New England), Squanto is the name of the devil in New England Native American pantheon. You'll find various gods in many mythologies and religions that somewhat fit the description of the devil
In most religions and theologies there are various forces at play whether it be angels fighting and opposing angels or gods fighting and opposing other gods. These gods or devils have to contend with other gods and/or devils to try to get what they want done.
I don't expect you to read the below but it is a possible description below why the holy book i attempt to adhere to is not dualistic.
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On that professor's notion of is Jesus Christ schizophrenic?
Its hard to feel completely comfortable with why Satan was created and why (despite predestination doesn't directly directly directly directly contradict free will) he allowed us to make bad decisions. The Bible says the God/Jesus Christ doesn't think the way man does. I speculate that prior to the creation of the angels and the mortal non living gods that God perhaps some measure felt for whatever reason to start creating entities beyond the Trinity. While I personally am not opposed to the idea of the Holy Trinity and I do not fall out side of the orthodoxy of Trinitarianism, I do believe focusing on the theology of Trinitarianism as though it was core Christian belief, changes our focus from Jesus Christ's personality to some lesser Biblical truth. I don't believe Trinitarian theology is paganism but I feel the Christian church should focus on the personality of Jesus Christ as laid out in the old testament and the new testament. And once again a careful reading of the major prophets of the old testament will reveal a God and also a Jesus Christ that truly showed compassion to the people of the old testament and also to the people of the new testament. Now many will say that Jesus Christ wasn't alone before he created the angels and the other entities however perhaps my frailties make me fail to see beyond the idea that if i'm inclined to play a video game or build a tower out of a deck of cards, that there is either a sharp or dull impulse to push me towards that endeavor. We people have a God given dna and also a nurturing of our development (the situations we are put into) that sharply influence are predispositions. God/Jesus Christ I would argue based on the name Jehovah ("I_AM" or "I_AM_WHAT_AM", the latter being a questionable interpretation as far as I know) does not inherently know his origins nor can give a complex answer that caused him to have the personality that he has. We don't have that "problem". So let me speculate that when Jesus Christ decided to start creating the angels, mortal non living gods and other entities I believe under my understanding of what i consider rational, the actions of Jesus Christ/God in the beginning are sometimes attributed to what would commonly be called true randomness (as opposed to computer generated randomness or even the seemingly random nature of our Universe). I'm not saying that the personality of God/Jesus Christ is random but that due to my frailties I don't know how to describe this concept in a more accurate way.
So at some point he created entities that do not include the Trinity (I suppose the Trinity existed outside of time and forwards and backwards through eternity). I also speculate God/Jesus Christ spent time in the beginning just sitting there trying to understand what was going on before he started creating entities. I also speculate the time period prior to this "age" or self awareness loops around and some how pushes Jesus Christ into a sort of looping God/being that exists outside of time and thus you could say the time before time should more accurately be defines that substance or deity always has existed outside of time. Most of what i am writing in this post is my own speculation (perhaps shared by many Christians).
When he created the entities such as angels or mortal and non living gods, did he create them as spiritual or "physical" creatures (angels are created so you could say they are creatures). To my current understanding of the Bible the angels and mortal non living gods are spiritual. The question i ask is to what degree do these creatures have the tendency to mimic their creator. To what degree (1 to 100%) is their conduct predictable. Humans are 100% predictable but are gods or angels 100% predictable. And once again is 1% or 100% predictable? Satan was actually number 2 to Jesus Christ right from the beginning. Many of the demons to my understanding were in fact angels at one time. For now on i will refer angels (perhaps good servant gods) as angels and bad angels and also demons as "bad gods". So we have the Trinity, the angels and then the bad gods.
At some point Satan betrayed Jesus Christ/God and so on and so on.
Why do I say in the classical sense that Jesus Christ/God is not schizophrenic but at the same time Christianity is not a dualist religion. The Bible says
that God does not think at all like the way people do, so let me say this: I speculate the need to create Satan as to some degree inferior to the Trinity was in compliance to the basic logic that if you were an ancient warlord or ancient king, your ruling was not based on a hereditary nature but your kingship was attained through merit. This is not something you can say for modern kings. I speculate God/Jesus Christ gave Satan to some degree an inferior nature to the Trinity because this is not unkind but it is simply logical and rational. I would argue this could be said of all entities and it even carries over into the creation of people but I speculate that the relationship between the former concept and intended human frailty is atleast mildly close but it might not even qualify as a linear relationship (and ofcourse not one to one considering a one to one relationship is a type of linear relationship).
I would like to speculate and here i have much misgivings about this speculation (keyword speculation) that Satan surprised to some degree God/Jesus Christ considering his nature was spiritual rather than matter. I do believe perhaps matter and energy can be built from spiritual substance but perhaps we could say matter and energy is an extremely complex dancing of spiritual forces that vibrates continuously and makes matter and energy have the qualities that we witness on a daily basis. Perhaps dealing with Satan is like my brother playing me (the opponent) in chess, my brother is much smarter than me and will probably will win the match but he must stress slightly over the issue. I would argue if Jesus Christ played any human in chess, the match would in all practicality be over before it started considering the realities of Scientific determinism. Jesus Christ, I speculate, stresses to some degree when dealing with non living gods but when dealing with people the results of what would happen came in before anything took place. My last speculation is that to some small degree Jesus Christ acts as a sociopath only in the sense that he does a criminal profile of all the entities he ever created. In that sense (and i stress this is a very remote and vague relationship) to some very small degree that God/Jesus Christ can be said to have minor similarities to someone who has schizophrenia.
I will go on to further to say in the end each Christian will never worship another Christian, but we the Porcelain chess pieces on his chess board will be all worshiped by the living God. Is it lawful for God to love and adore his wife (The Christian Church). I speculate that it is. We the christians were used as living sacrifices to manipulate the great spiritual powers (angels and non living gods) that were in Heaven.
On why God/Jesus Christ gave us inferior and imperfect dna as opposed to perfect dna like himself, I speculate there are various reasons for that: going beyond the fact that Jesus Christ achieved his status as an ancient king or warlord achieves his status being not through heredity but through merit, I believe among many other reasons, Jesus Christ wanted to show love to an animal similar to him and to love an animal not because of what that animal can do for him but for what that he (Jesus Christ) can do for that animal. There is only one marriage or sexual relationship in heaven and for all eternity and that the marriage between Jesus Christ and the Christian Church. Once again just about all of this falls outside the pale of orthodoxy and is mostly speculation.