Parenting

No one said parenting would be easy but I sure do wish someone would have told me about the times that will make your heartache.  For the past month or so my 8 year, who is normally a really good kid, has decided he was going to get this attitude like he runs the house.  I let it go and just brushed it to the side for the first week because I thought well if I just ignore it he will stop.  Boy was I WRONG, it has just gotten worse.  Last night we were at the ball fields (our second home) and Christian was wanting to go to a friends house, I told him no because it was a school night. Well he came back at me with an attitude from hell.  Of course it was embarrassing because here we are out in public and my 8 year is attempting to tell me what he is and isn't going to do........straight to the car we went.  On the ride home I asked him what his problem was and proceed to tell him that the attitude he has been getting was ending right there and now.  My response from Christian was "Mom I'm really sorry, I don't know why I act this way, the devil must have a hold of me." My heart began to break, that is not something that a mother wants to hear.  I felt like a complete failure.....not only have a failed my son but I have failed our God because here my 8 year old is telling me that he has the devil is inside of him.  At that moment in my heart I prayed to God that this would change, I asked for God to show me the correct way to rear my child, the way to Him.  All I could say to Christian was WE need to start praying more, actually I really didn't know what else to say for once my tongue was tied.
Me being me it's hard to ask for advice but here I am asking for some tips on not only how to control my sons fierce attitude but how do I get him to feel like the devil doesn't have control of him??