This saying is evidence of the superstition that underlies the lottery. The lottery derives from outmoded ideas that a human sacrifice appeases the gods and leads to a bountiful harvest. Even though the story is set in the supposedly modern era, the village and most of the villages near it still cling to the theory that the harvest will suffer or fail without the sacrifice.
The story illustrates the extent to which outdated or patently false ideas can take hold of a society. Tradition is a very powerful force, as the story shows, even when it is seemingly senseless and destructive.
While the rationale the story gives for stoning a community member to death is to ensure a good harvest, philosopher Rene Girard would argue that the ritual killing has another purpose: anger, envy, and hostility, he says, build up in a community over time, and ritually killing a community member relieves tensions and aggressions, allowing the survivors to live in relative peace.