There is a phrase that drives me up the wall - Judeo-Christian. There is no such thing. Judaism is a religion unto itself, as is Christianity. True, they share certain concepts as would be expected from a situation where one culture and beliefs gave rise to the other but after they separated around 100 C.E. each evolved greatly in both their theology and their culture. Most religions have basic concepts in common with other other religions albeit expressed in different ways. Rabbi Hillel said "What is hateful to you, do not do to your neighbor: that is the whole Torah while the rest is commentary; go and learn it." Much of what separates various belief systems is the commentary which makes it such a tragedy when members of various belief systems can't get along or feel that theirs is better than all the others; a feature inherent in only 2 religions I know of - Christianity and Islam.
I have just read another article by a Pagan expressing their frustration at being asked whether they worship the Devil. I do not fault her in the least for her frustration at such questions but what really grated on me is her constant references to Judeo-Christian attitudes. Unfortunately this is not an uncommon mistake. One of my pet peeves with those who don't know Judaism, but think they do, is that they lump Judaism in with Christianity and assume that just because a concept or attitude is prevalent in Christianity it must appear in Judaism as well. Judaism is NOT an older form of Christianity. It is NOT Christianity sans Christ and it DOES NOT include a supreme personification of evil that Christianity calls Satan or the Devil.
We have our fair share of malevolent beings that can and do cause havoc with humanity but our sages had the wisdom to see that one does not need to have the stimulus to do evil forced on us from outside ie. a corruption of the soul as one sees in the concept of Original Sin or the idea "the Devil (or one of his minions) made me do it". We know that we can get ourselves into enough trouble thank you very much. In Jewish belief a person is created with both the yetzer ha-ra (evil inclination) and yetzer tov (good inclination) and it is up to us to decide on a case by case basis which one we are going to listen to. There is a character mentioned in the Tanach that is referred to as satan or ha-satan but rather than being seen as an equal and opposite entity to G-d both in power and intention this character is more along the lines of a prosecuting attorney continuously trying to prove that humanity is not worthy of a just decision in it's favor or G-d's mercy. Literally ha-satan means 'the accuser' but other than being recognized as being a pain in the butt, does not play a large role in Judaism. There are other demons that Jewish tradition has felt much more need to guard against.
To the best of my knowledge, the concept of an evil diety that is just as powerful as the diety of light first appears in the ancient world ca. 1000 BCE in the religion of Zoroastrianism. Considering that Torah was not written down until the Babylonian Exile ca. 586 BCE it is likely that the inferences to such a being got incorporated into Judaism and therefore Christianity by being part of the culture surrounding the scribes as did many things in Torah such as many of the legends found in Bereshit (Genesis).
I only wish Pagans would quit lumping Jews in with Christians when addressing the injustices that have been perpetrated by some Christians and the prevailing Christian culture against them. Jews have suffered from much the same sort of ignorance and intolerance and being a nature based religion it has much more in common with Pagan belief structures than Christian ones. I read another article that addressed this very well; it's uncanny how much her and my background, at least in general, and ideas are similar.
Now that I have ranted enough about Judaism and Christianity being lumped together, in the interest of fairness I must point out that European Judaism was greatly affected by Christianity during the Middle Ages, just as Jews have been affected by the ideas and practices of any culture they have lived in, and a lot of Christian ideas found their way into Jewish philosophy and practice. It is one of the things that I find regrettable about Judaism and one of the reasons I break from conventional Judaism looking more for the core beliefs and practices - the pagan Judaism so to say. Whichever form of Judaism one practices though, it is not Christianity and does not include the Devil.