Is this a theme from "The Scarlet Letter"?

I have to study the Scarlet Letter the summer and come up with themes. One of themes that I was thinking about was "Sin vs. Evil". By sin I mean Hester. She cheated with Dimmesdale, but she did it out of love and with no intent to harm. Chillingworth, on the other hand, sought revenge on Dimmesdale; his sin was done solely with the purpose to harm and was therefore evil. Would using this theme be too much of a stretch?