To emphasize the spiritual danger his audience is in, Edwards often relies on imagery of a hungry hell or devouring devils, as seen in this passage:
The Devils watch them; they are ever by them, at their right hand; they stand waiting for them, like greedy hungry lions that see their prey, and expect to have it, but are for the present kept back; if God should withdraw his hand, by which they are restrained, they would in one moment fly upon their poor souls. The old serpent is gaping for them; hell opens its mouth wide to receive them; and if God should permit it, they would be hastily swallowed up and lost.
To be eaten by anything is unpleasant, let alone eaten by a lion or a serpent! There is no escaping a vicious predator that wishes to eat its prey, and here sinners are the prey that vicious animals will tear apart. This image of being eaten is visceral and contributes to the sense of imminent danger Edwards wants to create. Yet, in the midst of this terrifying imagery, Edwards characterizes God as merciful by his "restrain[ing]" of the devils, thereby urging sinners to repent and hasten to Christ without delay.
Also worth noting are the other literary devices Edwards uses to promote this imagery. Although it's not as impressive as his multi-paragraph spider simile, here Edwards writes that the devils which await sinners are "like greedy hungry lions." Likewise, "hell opens its mouth," a personification which allows Edwards to again call up the image of sinners being devoured.
Another one of Edwards’s characteristic long similes compares God’s wrath to a flood of water held back by a dam:
The wrath of God is like great waters that are restrained for the present; but they increase more and more, and rise higher and higher, till an outlet is given; and the longer the stream is stopped, the more rapid and mighty is its course when once it is let loose.
As Edwards has emphasized throughout the sermon, it is God and God only who protects sinners from both earthly harm and eternal damnation in hell. However, God’s protection comes at a cost—the longer he holds back his wrath, the greater it grows, just as a stream of water kept from flowing builds up pressure and will rush forth when released.
As with many of the metaphors and similes Edwards uses to illustrate God's wrath and restraint, the dammed water simile pulls from the audience's everyday experience to create a memorable visual. This and similar metaphors function like pauses in the logical argumentation of the sermon; they allow the audience a moment to fully absorb what Edwards is saying. They also give the audience a way to more quickly understand each point Edwards makes, which makes this sort of metaphor an especially important tool in a sermon delivered aloud.
Perhaps the most famous simile Edwards uses in this sermon is one that compares the sinner’s position to that of a spider over a fire:
The God that holds you over the pit of Hell, much as one holds a spider, or some loathsome insect, over the fire, abhors you, and is dreadfully provoked; his wrath towards you burns like fire; he looks upon you as worthy of nothing else, but to be cast into the fire.
Several constituent similes work within this larger comparison: God’s wrath is like fire, the sinner is to God as a spider would be to a human, and the precariousness of the sinner’s situation is the same as the precariousness of a spider that hangs above a fire by only a web. The visual of this small, easily destroyed creature hanging over a fire would have emphasized to the audience how small and helpless they were in the face of God's power.
Edwards aims here not only to, again, emphasize the horrible situation sinners find themselves in without realizing it, but also to show that God can throw them into hell at any moment and even has reason to. After all, a human would not hesitate to kill an insect, especially an annoying or dangerous one.