Well, in this fire and brimstone sermon, Edwards uses extended metaphors to argue that those who have not accepted Christ as their Saviour live on the brink of damnation and the torments of hell. Fear is used as he warns those who are not "born again" that at any moment God could drop them into the gaping pit of Hell. By focussing on the transitory nature of our lives, Edwards hopes to urge his audience to listen and accept his words, and repent and come to Christ to avoid such a terrible and flame-ridden fate.
One quote that to me suggests these elements is one drawn from near the beginning of the selection in my anthology:
So that, thus it is that natural men are held in the hand of God, over the pit of hell; they have deserved the fiery pit, and are already sentenced to it; and God is dreadfully provoked...
This quote makes the human condition from Edwards' perspective perfectly clear, stressing the fires of hell and indicating that it is our fate unless we do something about it quickly.