The phrase "his decency" is correct and usable in written English.
You can use it when describing a person's behavior or character, as in the sentence, "His decency in the face of adversity was inspiring."
But Ms. Hui lets his decency be revealed and grow.
Even in stills, his decency and charm come through.
A memoir of a good man murdered for his decency.
His decency, wit, friendship and common humanity were extraordinary.
More than all his titles, his decency is what makes him a champion.
His decency, and his faith in the cause, were never in doubt.
Bobby's palaver is meant to convince both him and her of his decency.
"His selflessness, his decency, his burning desire to help others has cost him his life.
"Like the remarkable Barbara Bush, his humility and his decency reflects the very best of the American spirit.
Juanes's trademark, besides his music, which combines the rhythms of cumbia with classic-rock guitar, is his decency.
Hosting is the ability to align one's charm — or, in Colbert's case, his decency and intelligence — with brands.
