I have found that middle of the road, non-fanatic religious people, have an easy time grasping the idea that the “devil” is just a representation or personification of bad behaviors by people. Nobody really believes that a little man runs around the world all the time making everyone do bad things, and that without this man that we would everything right. This is about as credible as believing that there is a little man inside our televisions or computers that furiously pulls levers to make it operate. Evil does not really come from the devil, but from human decisions, and we don't need a person to tempt us, because we tempt ourselves to behave a certain way, with the reward being the outcomes which we hope will occur.
Indeed, ha-satan or “the satan” really means “the accuser” or “the adversary”. However, when one thinks about it, one's conscience is one's accuser in many cases. Again, one does not need a separate, supernatural source of guilt. The adversary is our desire attempting to overcome the accusations of our conscience, which says that we should not use this means or that means to gratify our desires, or that our desires may not be healthy in the first place.
There is really very little biblical basis for this notion to begin with throughout the Old Testament. Most Judeo-Christians have a notion that there was some kind of battle in heaven between angels loyal to God and angels loyal to Lucifer, but actually, this story does not occur in the Bible. Notions of “Lucifer” appear to be based upon an Isaiah 14 prophecy where it is predicting that the King of Babylon, whom he dubs “son of the morning”, will lose his throne.
While the Bible does at times describe individual characters, such as an accuser in Job 1, or even tempters, such as the one Jesus experienced during his fast (see Mt 4), it is all completely understandable that these can be metaphors for temptation in general, and not a single, monolithic devil or satan character. Job's accuser, like our own accuser could actually be the thoughts of Job himself saying, “I wonder if I really could do the right thing if I lost all my material success”. In the case of Jesus his tempter is hunger itself, perhaps even induced from hallucinations due to food deprivation. Perhaps there was even a complete human tempter, as many of us have experienced when on a diet, saying "what's the big deal? Have some cake."
However, if there really is no devil, and he is really just a personification of evil then what of God? Couldn't we just as easily argue that, in the same way that we don't need a devil to explain human-caused evil, we don't need a God to explain human good? God too is a personification of all the things that we regard as proper, but that doesn't mean that a real being has to exist with those traits.
When the bible describes a final, epic battle between good and evil, perhaps what they are really talking about then, is mankind's quest to definitively settle the question of how we should behave. If such a battle is to take place at the end of the world then I wouldn't hold my breath, because settling such questions appears to be no closer now than in the days of Jesus or Moses.