I'm not sure how anybody can reconcile the existence of God and then personify satan as some kind of force in opposition to God arising from the same place as said, God. Evil created by God no less. Corruption forming in the presence of God is an astonishing belief, but such is religion, a series of astonishing beliefs.
That said, several religions will defend satan as some kind of reality equally as much as they defend the reality of God.
There are many pseudo scholarly articles trying to prove up satan but they never seen to place God in context with this satan which renders God as somewhat weakened in His own dominion and the foundational cause of evil.
Humans don't need a satan to be as they are, it is our animal nature dominating our spiritual nature. No satan required.
