Dimmesdale certainly cannot treat Hester as the rest of Boston treats her, simply because he knows that he is as guilty as she—perhaps even guiltier because he keeps his guilt a secret. He therefore treats her with more compassion and grace than others, and everyone loves him. Even when he tries to tell the town that he is the worst sinner among them, they just think that he is all the more pious and good. When he makes recommendations, others listen, and others observe his own behavior toward Hester, the sinner.
For example, when Hester approaches Governor Bellingham because she's overheard some discussion that people think Pearl ought to be removed from her care—as they judge her as unfit to be a role model and guide for a little Puritan girl—Dimmesdale defends her right to keep her child. He implies that God put Hester and Pearl together and so, if they separate the mother from child, they would seem to doubt God's judgment. Further, he argues that there is a sacredness to the bond between mother and child that one ought not to disrupt. He makes many compelling arguments that turn the tide of judgment, allowing Hester and Pearl to remain together. Mr. Wilson tells him that he has spoken "Well" and admits that "there is a weighty import in what [Dimmesdale] hath spoken." Dimmesdale's visible acceptance of and compassion for Hester seems to compel others to feel it as well.