Youth Ministry and Me

So recently I've been wondering whether as Christians our major fight is against sin (and our sinful nature) or the devil (and his devious and tempting ways).

I feel like I think, and my experience seems to match this, that my day to day battle is against sin and my own sinfulness rather than against Satan and his schemes.  I also feel like this makes good sense of a passage like Romans 7:7ff.  But obviously there are passages like 1 Peter 5:8 where we are told the Devil is our enemy/wants to eat us.

Has anyone worked this out or had similar questions?
Are there any good books on the subject?