The descriptions alone of Mrs. Merriweather are satirical. Lee has Merriweather's "voice soar(ed) over the clink of coffee cups" as she begins her "misguided people in this town" speech. This dainty, little, middle-aged woman is taking the stage in the very house of the man she's about to disrespect. In fact, her racial comments about her "sulky and dissatisfied Sophie" and her comments about how Atticus is not doing the right thing by representing a man who is Black set her up to fail. She is not only sitting next to one of Atticus' best friends (Maudie), she is in the same room as his sister and his daughter.
Lee uses this scene to show the reader how ugly racism is. That's how she uses satire. she takes the shortcomings of human behavior and makes fun of it--hopefully to bring about change. Hopefully the reader sees this and agrees that Atticus is doing the right thing and Merriweather is a bigot.
In Chapter 24 of To Kill a Mockingbird, Harper Lee satirizes the sanctimonious hypocrisy of self-proclaimed Christians.
The situation which Scout describes at the Missionary Tea is not atypical of the churches in the segregated South. While these churches might have had an African mission to which they contributed money and sent used eyeglasses and other goods, there certainly was no diversity in their local congregations.
Early in the Missionary Tea, the "most devout lady in Maycomb," Mrs. Merriweather, whose "large brown eyes. . . fill with tears when she considered the oppressed," extols the virtues of the missionary J. Grimes Everett, the only white man in Africa who goes near the "oppressed" in the "jungle." Further, when Mr. Everett returned home, Mrs. Merriweather informs the ladies that she told the missionary, "The ladies of the Maycomb Alabama Methodist Episcopal Church South are behind you one hundred per cent."
Shortly after this declaration of seemingly charitable thought and support from her congregation, Mrs. Merriweather launches into her none-too-subtle uncharitable criticism of those in Maycomb who do try to help African-Americans: "I tell you there are some good but misguided people in this town. Good, but misguided."
She adds that these people think they are doing the right thing -- a reference to Atticus -- but all they accomplish is to "stir 'em up." As an example of this discontent in "th)'em," Mrs. Merriweather says, "that church (the church of Reverend Sykes) ought to help her lead a Christian life," with "her" being Helen Robinson. Then, she mentions her maid Sophy, who is now "sulky" and "dissatisfied" with the "dollar and a quarter" she receives each week.
Hearing this hypocritical and insulting lecture by Mrs. Merriweather, Miss Maudie challenges the woman's lack of charity and insincerity by quietly asking, "His food doesn't stick going down, does it?" implying that Mr. Merriweather might choke on the food cooked by the maid Sophy of whom she has previously been so critical. Nevertheless,
the sanctimonious hypocrite, Mrs. Merriweather, continues her self-righteous conversation with Mrs. Perkins about Northerners, whom she dares to call "born hypocrites":
At least we don't have that sin on our shoulders down here. People up there set' em free, but you don' see 'em settin' at the table with 'em. At least we don't have the deceit to say to 'em yes you're as good as we are but stay away from us. Down here we just say you live your way and we'll live ours.
After listening to these women, Scout decides she is more "at home" in her father's world, where people speak more openly and honestly without insinuation.