I had been thinking for a long time that there is only one true sin, and that is the failure to life up to your own potential. I saw the major reasons that this happened as laziness and fear.
I finally watched the 1991 movie with Albert Brooks called "Defending Your Life" last weekend. It is great! In the afterlife, the movie shows how fear is the one really bad sin that will kick you back down to Earth again to learn through another lifetime. You keep getting smarter, using more of your brain, until you aren't paralyzed with fear anymore.
I see that Amazon.com has it available as a DVD. I'm thinking of buying it.