The main point in "The Lottery" concerns the nature of tradition and how it affects generations of people. Since the titular Lottery has always been practiced, the townsfolk seem to consider it just a part of life, and expected instead of rationally considered.
All the characters expect the Lottery to be performed each year, and for the victim to submit to their ultimate fate. Despite Tessie Hutchinson's protests, she isn't fighting against the Lottery itself, but against her family being picked; if someone else had been picked, she would likely have reacted as all the others, taking part in the ritual stoning. In this sense, her protests are aimed directly at her role, which is expected from all the other townsfolk; since they believe that their collective well-being rests on the Lottery being performed correctly, for her to refuse her fate would be unthinkable. As Old Man Warner comments, "There's always been a lottery."
When "The Lottery" was published in 1948, just three years after the end of World War II, many subscribers to The New Yorker magazine sent letters of outrage and many canceled their subscriptions over what they considered an outrageous, vile story designed only to shock the reader. In fact, some readers thought the story was non-fiction and wondered where in the United States such a thing could be tolerated.
Eventually, the controversy died and readers began to understand the story's intent, which is twofold: first, the story examines the nature of tradition, especially a tradition that people follow blindly and fail to question; and, second, human beings are capable of the most horrific behavior.
At first glance, the lottery itself appears perfectly benign--it takes place on a beautiful summer day in a peaceful agricultural community and it is
conducted--as were the square dances, the teen club, the Halloween program--by Mr. Summers, who had time and energy to devote to civic activities.
The lottery, then, becomes just another in a long list of civic activities, all of which appear harmless and typical of a rural American community.
We are told, however, that "the original paraphernalia for the lottery had been lost long ago," and the only remaining vestige of the original lottery is a black box, which incorporates pieces of the box that came before. Although black is an ominous color, most readers would not perceive anything wrong at this point. The only conclusion an astute reader might make here is that these people are following an ancient tradition whose origins are lost to them.
After the drawing starts, we learn from Old Man Warner that there
Used to be saying about 'Lottery in June, corn be heavy soon.'
For some readers, this might trigger the association between this lottery and fertility rituals common among many ancient cultures in which some kind of sacrifice occurs. A feeling of uneasiness might settle on some readers at this point, especially if they recall that the young boys were collecting rocks at the beginning of the story.
Clearly, the people of this community are following a tradition whose origin they cannot remember, and Jackson's point here is that tradition itself can be dangerous if those who follow it do not even know why they still follow it. Coming on the heels of WWII, in which millions of people were killed by people either carrying out orders or acting on traditional racial biases, the story unmasks a terrible truth about human nature--we follow certain traditions without questioning those traditions.
Jackson's second main point, which becomes obvious as the stones begin to fly at Tess Hutchinson, is that human beings, under the wrong influence, can be brutal beyond measure. What seem to be average, well-meaning, loving people can turn into brutes when their behavior is governed by something other than what we now call a "moral compass." In other words, the act of following a tradition relieves people from exercising rational judgment.
"The Lottery" articulates two truths: following a tradition blindly may lead to disaster, and people, no matter how outwardly civilized, can become brutes. And it is clear that Jackson, in creating such a horrific story, was thinking about the brutality of WWII that corrupted many "civilized" people.
The tried to show us to not believe in anything without think independantly even though a tradition can be started so long ago but we need to think about it before we take actions.