Satan only exists in relation to God. Everything in the Bible is allegorical: a figurative, metaphorical representation of humanity’s fundamental understandings of life. ‘In the beginning was the word and the word was God.’ There was nothing else; everything was merged into God, even the potential for Satan to exist was within God. The concept of mankind was within God. All potential division and opposition was unified in God. Everything was merged into Source, in perfect union.
When creation took place, everything divided into contrasting, relative realities. All the animals, different from each other, male and female. Mankind also had opposition (but man being created FIRST and woman coming from his rib, I think, is just an attempt at subjugation and total human error in the rest of the allegorical bible story). The Tree of Knowledge of Good and Evil represents the adventure into this elusive reality of opposition, of pain and pleasure, dark and light, love and hate. The opposite of unification, of truth, of love, is selfishness, ego, arrogance. If God is the personification of love, then Satan is the personification of hate. It is a force on earth which keeps us wrapped up in selfishness and prevents us from feeling unity and compassion with the rest of creation. It’s all part of the same system. Basically, Satan is ignorance of our higher self. And ignorance can be dispelled by knowledge.