The character of Satan hardly has any presence in the Hebrew Bible. Jews generally don't view Satan as a form of major adversary to their god- that concept came later. I don't know what Christians realize when they propose a major enemy that Jews never particularly acknowledged at all.
With Persian/Zoroastrian influence, later ideas make it so that this Satan is against God. It's like a big action/war movie- it's always better with a villain. The snake in Eden that was never specifically described as Satan was identified as Satan anyway. But he surely was a bringer of light if he was willing to gave mankind knowledge in the story when god was not.
It seems to me that Christianity, with Jesus, Mary, and Satan, and in some cases, saints that people pray to, has polytheist leanings. In some doctrines, the Satan character has a power level that rivals or exceeds Greek gods.
Omnipotence excludes the possibility of any sort of legitimate villain. The propositions of omnipotence and omniscience are such that everything is in control and every threat is negligible or part of the plan.
Most representations of the Christian Devil are actually amalgamations of concepts and representations of pre-christian gods.
One religion's devil is usually the previous culture's god. It all hinges on the fact that history is always written from the perspective of the conqueror.
Religion was long ago recognized as an effective tool to control the "raging masses"
Like any tool, religion can be used for good or evil.
Egyptians had the concept of Maat. Maat, like Karma, was a force that bound all things together. It represented upholding the laws of justice harmony, unity and balance.
The Egyptians believed that at the end of days ones deeds in life were weighed on the scales of Justice. If you were found to light you were fed to a monster and that was it.
The evolution of the concept of some kind of punishment in the afterlife and the introduction of the "fear factor" increases the effectiveness of religion as a means of control.
Zoroastrianism has the concept of everlasting punishment in Hell. Christianity also relies heavily on "the fear factor". Don't question, believe or suffer. This combination of enforced ignorance (don't question) coupled with fear of eternal punishment was a fantastic way to subdue the masses. Divine right, Pontifex Maximus, codify the ideas that some human speaks for God so you better not question anything that person says.
Should you question you will face the possitility of not only earthly suffering but eternal suffering. Children raised from birth in this doctrine have a build in subconscious aversion to questioning certain religious beliefs so a high percentage dont.
Satan was introduced as the ultra evil sadistic fellow that oversee's hell. This character and demonic images serve to cement the "fear factor" into the minds of adherents.
The next evolution of the "fear factor" was the Quran. On almost ever second page you will find .. Do this and suffer, Dont do this and risk the eternal fire .. over and over .. in many different varients the Quran reminds adherents what awaits should one not believe and obey.
