Trouble with Demons

Many people tell stories about personal experiences with demons and those sorts of things. I have very close friends for whom I carry a great deal of trust and respect that have shared such experiences with me and I believe that those experiences were real. I have personally never had any such experiences that I am aware of and I understand that the idea of demons has changed throughout history. My only problem with the idea is that it makes it too easy to avoid responsibility for our sin. "The devil made me do it" is a theological problem for me because it takes responsibility off of us. I think that the idea of personal responsibility goes hand in hand with the idea of repentance. If we are merely victims of the "devil" we don't really have anything to repent of, only the "devil" and demons and such would need to repent since they would be the ones with the responsibility. This is only the beginning of the theological troubles that surround this idea in my mind.