An appropriate definition for hypocrisy as it pertains to the subplot of Chapter 24 of To Kill a Mockingbird is one given by Dictionary.com:
a pretense of having a virtuous character, moral or religious beliefs or principles, etc., that one does not really possess.
This definition is exemplified in the character of Mrs. Merriweather, "the most devout lady in Maycomb," who is purportedly very concerned and passionate about the African missionary work of J. Grimes Everett, and "whose brown eyes always filled with tears when she considered the oppressed." She does not, however, extend this Christian charity at home. Instead she complains about Maycomb's black community and even Atticus Finch. So though Mrs. Merriweather thinks she is "devout," she doesn't apply these values consistently.
That she does not truly possess the Christian virtues of compassion and charity and love for all men that she purports to have is evinced in her conversation in which she speaks of forgiving the black community of Maycomb for their dissatisfaction over the outcome of the Tom Robinson trial as though what has occurred has been just. She complains about her maid's surly attitude and says that she would have fired Sophy if she had continued with this attitude.
"It's never entered that wool of hers that the only reason I keep her is because this depression's on and she needs her dollar and a quarter every week she can get it."
Her uncharitable attitude is further exemplified as she subtly alludes to Atticus in his own home:
"I tell you there are some good but misguided people in this town. Good but misguided. Folks in this town who think they're doing right, I mean."
Mrs. Merriweather complains that such people are the ones responsible for "stirring them up"; that is, getting the black community upset about the unjust treatment that they receive, particularly in light of what has happened to the innocent Tom Robinson. So, while she hypocritically praises the work of a missionary overseas, at home, Mrs. Merriweather does not extend any Christian charity to the plight of the black people or to those who have tried to help any of them. She only gives it lip service if work is done for the Africans thousands of miles away.