In looking for quotes on ambiguity, reexamine the treatment of Arthur Dimmesdale by the community. He is one of the central characters whose existence and actions illustrate ambiguity. He has this secret sin in his heart which he is incapable of (or unwilling to) admit, yet the entire community holds him up to be a pillar of virtue and morality. Then, when he finally does confess his sin, the people don't hate him; instead they say, "Oh, what a good man to admit his sins!" (My paraphrase, by the way! :)
Check the link below for information about this important theme, then have your group reexamine Arthur Dimmesdale - I think you'll be able to find suitable quotes, especially if you look closely at how the townspeople talk to and about him.