I know that A is for adultery for hester and it is also for her artistic ability, but I need a sin that associates with Dimmesdale and Chillingworth. It doesn't have to be long I jest need a word to describe their sin.

If you click on the following searches and read and study the material that can be found via clicking on some of the links, it's likely that you will be able to come up with the word that you need.

What sin does Dimmesdale and Chillingworth do in the Scarlet Letter? - Google Search

What sin does Dimmesdale and Chillingworth do in the Scarlet Letter? Wikipedia - Google Search