What emotion is Jonathan Edwards trying to invoke in order to motivate people to live a good Christian life in "Sinners in the Hands of an Angry God"?

In this sermon, Edwards strikes a chord of terror in his audience in order to convince them to accept Christ and therefore avoid the nightmares of Hell. He uses numerous images in order to elicit this emotion:

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.

In this quote, Satanic angels are said to be lurking around those who haven't accepted Christ. He compares them to lions in search of prey, therefore making them more powerful than humanity. All that restrains these demons from taking the souls of those whom they seek to devour is the hand of God, who constantly holds them back. Edwards asserts that this could happen at any moment, and the "lions" would then be unleashed on the souls of their victims, taking them to the depths of Hell.

The God that holds you over the Pit of Hell, much as one holds a Spider . . .

This image of God dangling unbelievers over the depths of Hell like a spider is a vivid and symbolic image. It both produces an image of helplessness (the spider is totally at the mercy of the hand which holds it) and conveys the symbolic representation of God's distaste with unbelievers. Spiders are vile little creatures, pretty much "loathsome."
Through strong tone and striking imagery, Edwards seeks to convey to his congregation the importance of living in accordance with God's will and under His principles.