This story was updated Oct. 10 at 4:12 p.m. EDT.
The devil goes by many names — Satan, the Prince of Darkness, Beelzebub and Lucifer to name a few — but besides this list of aliases, what do people really know about the brute? That is, how did the story of Satan originate?
Many ancient religions have scriptures detailing the struggle between good and evil. For instance, in the Zoroastrian religion, one of the world's earliest, the supreme deity, Ormazd, created two entities: the chaotic and destructive spirit Ahriman and his beneficent twin brother, Spenta Mainyu, said Abner Weiss, a psychologist and the rabbi at the Westwood Village Synagogue in Los Angeles.
"The ancient world struggled with the coexistence of good and evil," Weiss told Live Science. "They hypothesized a kind of demonic, divine force that was responsible for evil, arising out of the notion that a good god could not be responsible for bad things."
Related: Was the 'forbidden fruit' in the Garden of Eden really an apple?
However, Satan was not a prominent figure in Judaism. There are few demon-like figures in Hebrew scripture, but the most famous one appears in the Book of Job. In that book, an "adversary" or "tempter" asks God whether the prosperous man Job would continue to praise God after losing everything. God takes up the challenge, and strips Job of his wealth and family, leaving the man wondering why such a horrible fate befell him.
But in this story, God wields more power than this adversary; as such, this evil tempter challenges God, who then takes away Job's fortune, Weiss said.
"[Judaism] found the notion of God having to share authority as limiting the omnipotence and even the omniscience of God," Weiss said. "And therefore, Satan was never personified as a source of evil that was equally powerful."
But Satan did become a part of certain Jewish sects beginning around the time of the Common Era, when Jesus was born, Weiss noted. Moreover, Judaism's mystical teachings, called the Kabbalah, mention a light side and a dark side, but the dark side is never given equal power to the light, Weiss said.
Any Sunday school student can tell you that Satan is a fallen angel, but this fall actually isn't described in the New Testament, or the Christian bible, said Jerry Walls, a professor of philosophy at Houston Baptist University and author of "Heaven, Hell and Purgatory: Rethinking the Things That Matter Most" (Brazos Press, 2015).
However, Satan suddenly appears in the gospels as the tempter of Jesus, with nary an introduction of how the evil presence got there. So, Christian theologians have come to this conclusion: If God created the universe, and everything God creates is good, then Satan must have been something good that went bad, Walls said.
"The only thing that can go bad by itself is a free being," Walls said. "Since there was evil before human beings came on the scene, the inference is [Satan] must have been a fallen angel."
There are other references to Satan in the Bible, depending on different interpretations. The Hebrew Bible has two passages about people who aren't respectful toward God. In these passages, Isaiah 14 and Ezekiel 28, human rulers make outrageous boasts, and some Christians interpret these actions as expressions of Satan, Walls said.
Moreover, the gospel of Paul in the New Testament refers to the snake from the Garden of Eden as Satan, though the snake isn't described that way in Genesis, Walls said. In this sense, the snake and Satan can be seen as tempters that try to get people to disobey God, but aren't always successful, Walls said.
Related: Why does Christianity have so many denominations?
"The first Adam fell to the temptation of Satan," Walls said. "Christ is described as the second Adam, who successfully resisted temptation."
Satan as "the enemy"
Satan can also emerge as the enemy — the "other," or an "outside" group.
"I thought of Satan as a kind of a joke, kind of a throwaway character," said Elaine Pagels, a professor of religion at Princeton University and author of "The Origin of Satan" (Random House, 1995). "In the Book of Job, he's practically a device to explain what happened to Job."
The Hasids, a Jewish sect whose name translates into "The Holy Ones," were the first group in Judeo-Christian history to seriously discuss Satan, she said. The Hasids lived just before the Common Era and didn't like how the Romans and some of their Jewish collaborators ruled their country, Pagels said.
So, the Hasids withdrew from Jewish society and began preaching about the end of times, when God would destroy all of the evil people, "which meant all of the Romans and all of the Jews who cooperated with them," Pagels said.
The Hasids took a radical position: They said that they were following God, while their enemies had turned to the dark side, possibly without even knowing it. "So now, it's the 'Sons of God' against the 'Sons of Darkness,'" Pagels said. "It's a split Jewish group."
At this point of her research, Pagels had an epiphany, she said: The concept of Satan emerges when communities split. Radical groups want a clean break between themselves and their enemies, and so they describe their enemies as Satan, as devils who will one day face God's wrath.
"I realized that when people talk about Satan — like if somebody says, 'Satan is trying to take over this country' — they're not thinking of some supernatural battle up there in the sky," Pagels said. "They can give you names and addresses. They know whom they're talking about."
For instance, extremists might say, "America is the Great Satan." That's because "when people talk about Satan, they're talking about people, too," Pagels said.
The Hasids likely had a big influence on early Christianity, because Jesus and John the Baptist preached similar ideas to those of the Hasids. That is, they said that the end of the world was coming and that God wouldn't tolerate evil people, Pagels said. This meant the Romans and the people working with them, she said.
Turning an enemy into Satan is useful, she added. It suggests that "our opponents are not just people we disagree with — they're bad. You can't negotiate with them. You can't do anything with them, because they're essentially evil."
Editor's Note: This story was updated to fix an error about the number of demon-like figures in Hebrew scripture. The story previously said that Job was the only Hebrew book with a devil-like creature, but there is also one in the Book of Daniel.
Originally published on Live Science.