"Utter sincerity" means being completely genuine and honest, without any form of pretense or hiding the truth.
Sentences with «utter sincerity»
He looks her straight in the face, and with utter sincerity replies, «And you're a terrible judge of character.» (dvdtalk.com)
She plays this material with utter sincerity, which is a lot more effective than the movie's alternate strategy of giving its actors monologues that explain how their insane behavior has real emotional grounding. (avclub.com)
With all his utter sincerity and scorn of compromise, a rather surprising spirit of tolerance is shown by his disapproval when John the son of Zebedee reported that they had forbidden a man to cast out demons in Jesus» name. (religion-online.org)