Fulton J. Sheen said this quote

Very harmful effects can follow accepting the philosophy which denies personal guilt or sin and thereby makes everyone nice. By denying sin, the nice people make a cure impossible. Sin is most serious, and the tragedy is deepened by the denial that we are sinners…The really unforgiveable sin is the denial of sin, because, by its nature, there is now nothing to be forgiven. By refusing to admit to personal guilt, the nice people are made into scandalmongers, gossips, talebearers, and supercritics, for they must project their real if unrecognized guilt to others. This, again, gives them a new illusion of goodness: the increase of faultfinding is in direct ratio and proportion to the denial of sin.