Scarlet Letter- Why is dimmesdale important in the scarlet letter?

Dimmesdale hides a secret. Arthur Dimmesdale is a respected minister in Boston and the father of Pearl. While Hester waited for her husband to arrive from Amsterdam, she met Dimmesdale and had an adulterous affair with him, which led to the birth of their daughter. While Hester is publicly shamed for the adultery, Dimmesdale must suffer the ignominy quietly since no one knows of his culpability.