Throughout The Adventures of Tom Sawyer, Twain intentionally satirizes certain aspects of the mid-19th century American South in order to raise awareness of the hypocrisies and contradictions within that society. The religious revival that sweeps through town mid-way through the novel is one example of this:
When [Tom] got upon his feet at last and moved feebly downtown, a melancholy change had come over everything and every creature. There had been a “revival,” and everybody had “got religion,” not only the adults, but even the boys and girls. Tom went about, hoping against hope for the sight of one blessed sinful face, but disappointment crossed him everywhere.
Tom witness the effects of this revival after being bedridden with measles for only two weeks. The speed with which the revival occurs suggests that Twain is satirizing revivals he likely witnessed growing up in small-town Missouri. (Religious revivals were quite common in the South during this time period, though they did not occur quite so quickly.) Not only does the revival take over the entire town quickly, but it fades just as fast—Tom finds two of his friends who were piously quoting scripture one day eating a stolen melon the next.
With this device, Twain suggests that certain types of Christian religious devotion are not earnestly pursued but—rather—are the result of a fad and the desire to fit in, which is another example of hypocrisy in the novel.
One of the ways in which Twain satirizes the American South in the mid-1800s is by deciding to include an establishment called the Temperance Tavern and turn it into a secret drinking hole. Much like the religious revivals Twain includes in the novel, the anti-alcohol temperance movement was growing in popularity in the South and was rife with contradictions. (Historically speaking, many of the people who preached abstinence from alcohol were discovered to use it.)
In the book, Tom and Huck are children who still trust adults so take the Temperance Tavern to be what it says it is. Therefore, when they find Injun Joe passed out drunk in a room at the tavern, they decide that the place must be haunted:
“Don’t you see, now, what’s the matter with that ha’nted room?”
“Why, it’s ha'nted with whisky! Maybe all the Temperance Taverns have got a ha’nted room, hey, Huck?”
The boys’ reaction to finding alcohol in the tavern highlights the hypocrisy of adult society. Here, Twain is suggesting that rather than put their faith in their elders who teach them about moral purity, Huck and Tom need to grow up and understand that not everything is as adults say it is and that they need to develop moralities of their own.