Anti-System: the Fallen Angel

In a magical world where Dark and Light mages are revered more than the other mages, the only forces that can effectively fight the Erovian race, an invading battle-hardened race that evolved in a way to counter mystic elemental mages. Samael, a priest's son from the Divine Sanctum of Divinity, had an affinity to the Light Element but no talent in magic. Mocked and ridiculed, he keeps on doing good even if it is through being a training dummy for other mages to test their spells. Driven by his father's good teachings and his childhood friend's support, he kept going and never broke down. He reminded himself of the three Divine Axioms: God always protects, guides, and chooses the side of good. Perhaps this is the way given by God for him to become stronger. But in the end, he was mercilessly exposed to the true evil of the world. An evil that breaks the three Divine Axioms that he believed deeply. Samael's family was shattered by evil that does sins casually, and the System that is fated to be his way to justice was stolen by the person he trusted the most. Due to this horrible event, Samael was forced to confront the true nature of the world which leads him to meet with the Devil itself where all of his questions are answered. Was he genuinely talentless? Or does he not know his true elements? Was there really a happy ending for him? Or was God fated him to suffer evil and die a meaningless death? Is God real? Or is God simply a manifestation of the mind? Is there pure Good and Evil? Or are there only those in between? Once a good man turned into a person of evil, once a devoted man of God now turned into a non-believer, once a human turned into a Fallen Angel. Follow Samael's journey of vengeance as he makes a contract with the Devil and devoted his life to the Devil in order to achieve his vengeance.