I had a long talk with a Rabbi once at a friend's Jewish wedding. One of the things we talked about the stuff that's NOT in the Torah that is for some reason in the Old Testament. (Note: The entire validity of the Christian faith comes from it's supposed relationship to the Torah, which is supposed to be the Old Testament translated from Hebrew. It's very much not.)
No Devil. The only being that was anything close was "The Adversary" who was like the prosecuting attorney for God.
Hell is not permanent. It's a place you go where you see what your life could of been if you had been a better man. Jews also believe in re-incarnation.
There was no "war in heaven" and no "rebellion". Angels can't rebel. They don't have free will.
They were also highly accepting of other people and their religions. Even mine. When I asked the Rabbi why they said it was because they believe that all genuinely good people go to heaven. You don't have to be a Jew. And if you don't get it right the first time you get to come back and try again.
When atheists spend a lot of time arguing about whether or not Jesus existed I generally say they are barking up the wrong tree. Jesus is not the problem. All the bullshit done in the name of chasing down the fictional "Devil" and his human minions is what the problem is. Crusades, burning heretics, etc.
This documentary does a great job of debunking the "Satan" myth and gives the historical basis for how this entity was created and inserted into the Christian religion. Why? Because a church that teaches people that submitting to the church is not necessary to get into heaven does not have too much power.
That's only an hour. If you still believe in the devil after that fine. I respect other people's rights to believe whatever they want. All I ask is that they look at the evidence. And not try to force those beliefs on anyone else.