Rituals are a part of life. A society or culture completes them without thinking about why they do; it's just something that has always been done. While rituals can unite communities and give them a sense of comfort, communities can rely on rituals even when they've grown out of date or dangerous.
In Shirley Jackson's short story "The Lottery," she describes a town's ritual. Each year, the small town gets together to draw names. The winner of this lottery has rocks thrown at them by their community. The horrific scene turns neighbor against neighbor and even families against each other, as every member of the town is expected to participate. Jackson reiterates the ritual nature of the lottery to point out that the town doesn't know exactly why they host the lottery every year. The narrator discusses changes that have occurred over the years (“Because so much of the ritual had been forgotten or discarded, Mr. Summers had been successful in having slips of paper substituted for the chips of wood that had been used for generations") and mentions that it has even been suggested that they cancel the lottery. However, this thought is dismissed when the town's oldest citizen, Old Man Warner, is quoted saying, "lottery in June, harvest soon"—a line that sounds rhythmical, like another ritual, repeated throughout the years.
The suggestion of an annual town murder would not be accepted in modern society, but because the town has embraced the act as a yearly ritual that everyone participates in, the act is not questioned by the citizens of the town.