In "Sinners in the Hands of an Angry God," Jonathan Edwards asserts that damnation "does not slumber; it will come swiftly, and, in all probability, very suddenly" upon those who least expect it.
Edwards expects damnation to come quickly for those he feels are not assured of their salvation. In another part of his sermon, he maintains that many delude themselves into trusting their own "schemes" for ensuring their place in heaven. He argues that it is futile for men to "contrive" for themselves. Rather, he asserts that "whatever pains a natural man takes in religion, whatever prayers he makes, till he believes in Christ, God is under no manner of obligation to keep him a moment from eternal destruction."
In yet another part of his sermon, Edwards tries to frighten his listeners into action. He portrays hell as a place that has been steadily and unequivocally set aside for all sinners. He assures them all that "their damnation does not slumber; the pit is prepared, the fire is made ready, the furnace is now hot, ready to receive them; the flames do now rage and glow."
Basically, Edwards believes his stark portrayal of the horrors of hell will induce his listeners to take the necessary steps towards their own salvation.