*Is* The Devil Real?

I have a hard time reconciling the fact that the Devil is real in the Bible with the idea that he might be alive and real in our world as well; Jesus talks to him, sends him off – demons enter people, and animals… but in my own life, I can’t help but think that when I have a hard time with my own faith, and getting closer to God, it’s anything other than a failing on my part. I don’t think that it’s the Devil influencing me, because then I feel like I’m not taking responsibility for my actions. It just feels… I don’t know… shoddy, to say, “The Devil is tempting me to think against God, or to sin – I would be closer to God if not for him”.

How are you supposed to tell the difference between an intrusive thought, and the actual presence of the Devil in your mind? How can you tell if it’s the Devil, or people simply being evil because they have free will to do evil? I just don’t know…