Why does edwards claim that nonbelievers are akin to spiders in "Sinners in the hands of an agry God"?

This comes from Jonathan Edward’s famous sermons, "Sinners in the Hands of an Angry God." It is said that he read this sermon dispassionately, in a monotone voice, which only heightened the sense of shock and horror at the God he was portraying. When people heard him describe God in such a fashion, many fell to the floor, weeping, wailing, and crying out in terror for their very lives. It was considered to be a great "revival sermon." I am shocked by this sermon as well, but for completely different reasons. Jonathan Edwards is widely considered to be America’s greatest theologian, which I find terribly disturbing.