Dr. Hawkins explain karma very well in this podcast:
David Hawkins, M.D.Ph.D. Beyond the Ordinary Dot Net
March 8th, 2005 : Karma
If Karma is too hard to reconcile, just use "level of consciousness" instead, they pretty much mean the same thing. With every "sin" you make, you lower your consciousness level, with every positive choice you make, you raise it. Your choices and experiences and perceptions reflect the level of consciousness you are currently at (karma).