Theism in the world rests on the belief that God is all-powerful; he is omniscient, omnipotent and omnipresent. Being the creator of heaven and earth, and all beings within, He is a God of love and compassion who dotes on His creations, and would not let anything harm even the hair on their heads. But the belief in God is always accompanied by the belief of the existence of evil, a force determined to pull His believers away from the light and into darkness and destruction. An ever-loving God could/would never allow for the existence of evil, from His own free will. This points to the existence of an equally powerful being, God’s archenemy, Satan.
Ancient religions, particularly those which are monotheistic
were conflicted because of the existence of pain and suffering despite there being the protective gaze of an omnibenevolent God. It led to widespread atheism until the idea of Satan being the originator of evil came into being.
It released God from the accusation of being hypocritical, and more importantly, the perpetrator of pain and darkness.
With Satan, the idea of God being pure goodness is amplified. This allows for a strengthening of one’s faith in Him as the protector of all. Theodicians often quote the Bible to showcase the numerous instances where God is separated from Satan. In Ephesians 6:11-13, it is stated to wear the armor of God in the battle “against the rulers, against the authorities, against the cosmic powers of this present darkness, against the spiritual forces of evil in the heavenly places.” Similarly in the Gospel of John, it is stated, "The Son of God was revealed for this purpose, to destroy the works of the devil."
This proves that evil is the creation of the devil, better known as Satan, while God has always provided unconditional love and protection to His people.
With the belief in place that God is good and Satan is evil still comes the question of why God would allow Satan and evil to exist at all. This belief explains only the origin of evil, but not the why of evil. And if a good God would not allow evil at all, then why does evil exist? Theodicies do not explain why God allows evil.