The world at large is run by two natural forces. The good and the bad, the moral and immoral, the positive and the negative, the God and the devil. This forces are disclosed in our characters and actions even as human beings. This does not mostly depend on how you were brought up or what you grew up knowing and understanding. SO the devil actually exists and he is associated with all that is immoral, negative, evil and bad. There are some people who actually do not know anything about religion but they know how to do good to others.