What "widely diffused opinion" began to circulate in the town regarding Chillingworth's relationship with Dimmesdale?

They believed Dimmesdale was haunted either by Satan himself or by Satan’s messenger in the form of old Roger Chillingworth.

Some people in the town believed that the "hand of Providence." had brought the two men together....... others were prejudiced against Chillingworth.

"And the Reverend Arthur Dimmesdale’s best discerning friends, as we have intimated, very reasonably imagined that the hand of Providence had done all this, for the purpose,—besought in so many public, and domestic, and secret prayers—of restoring the young minister to health. But—it must now be said—another portion of the community had latterly begun to take its own view of the relation betwixt Mr. Dimmesdale and the mysterious old physician. When an uninstructed multitude attempts to see with its eyes, it is exceedingly apt to be deceived. When, however, it forms its judgment, as it usually does, on the intuitions of its great and warm heart, the conclusions thus attained are often so profound and so unerring, as to possess the character of truths supernaturally revealed. The people, in the case of which we speak, could justify its prejudice against Roger Chillingworth by no fact or argument worthy of serious refutation." (Chapter 9)