Good and Evil

I've been thinking a lot lately about good and evil, and how our choices define us as individuals. Do good people do good things because they want to, or because they want to appear good? If it's for the second reason, as I suspect is the case of many people - myself included, occasionally - then the good deed is being done in the name of pride, which is a sin, essentially doing something good for a bad reason. Being good, then, simply isn't enough; you have to be good sincerely. And sincerity is even harder to fake than being good.