Jonathan Edwards, an eighteenth-century Puritan minister, was part of a movement known as the Great Awakening. His sermon, although grounded in the theological principles of Calvinism, was not intended primarily as an intellectual argument, but rather a deeply visceral appeal to the emotions of his audience to impress upon them the need for a genuine conversion experience.
The sermon is based on the Biblical text “Their foot shall slide in due time.” (Deuteronomy 32:35) that emphasizes God's anger at the sins of the Israelites. The image Edwards develops from this text is that of humanity walking on a slippery slope on the edge of the abyss, or Hell.
Rather than emphasize the benevolence of God, this sermon focuses on the anger of God at sinners. In the eyes of God, sinners are as disgusting as a spider. The visual image of a spider suspended by a single thin thread over a burning pit emphasizes both the vileness of the sinner-as-spider and the frailty of the single thread that is preventing the spider from falling into the flames. The thread connecting the spider/sinner to God is composed of both human faith and God's sacrifice of his son Jesus and the mercy of Jesus. If the thread fails, either through the wavering of the sinner's faith or God's will, the sinner falls, and is consumed like a spider dropped into searing flames.