What purpose does Jonathan Edwards's sermon "Sinners in the Hands of an Angry God" serve?

Jonathan Edwards gave his "Sinners in the Hands of an Angry God" sermon because he felt a great burden to see unsaved persons turn to Christ, which he believed was the only way to God and eternal life. In this sermon, Edwards describes vivid pictures of the dire situation of those not in favor with the almighty God.
He says, “The Use may be of Awakening to unconverted persons in this congregation” (see the entire sermon here).
Edwards's purpose and use of powerful, persuasive language is excellently displayed in this excerpt: 
“So that thus it is, that natural men [i.e. people in their present state; unrepentant] 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… and they have done nothing in the least to appease or abate that anger, neither is God in the least bound by any promise to hold 'em up one moment; the devil is waiting for them, hell is gaping for them, the flames gather and flash about them, and would fain lay hold on them, and swallow them up; the fire pent up in their own hearts is struggling to break out; and they have no interest in any mediator, there are no means within reach that can be any security to them. In short, they have no refuge, nothing to take hold of, all that preserves them every moment is the mere arbitrary will, and uncovenanted unobliged forbearance of an incensed God” (Sinners in the Hands of an Angry God). 
With these frightening words, Edwards is saying that we, in our natural state — as we are born — are sinners. We have blatantly and irrevocably offended an all-powerful God, and are now hanging by a thread over the mouth of Hell. The only thing keeping us from suffering in horrifying anguish is that God’s will has not decreed us to die — yet.
Edwards does not leave us to complete despair, however. There is hope for salvation from this damnation. He says, “here you are in the land of the living, and in the house of God, and have an opportunity to obtain salvation.
“And now you have an extraordinary opportunity, a day wherein Christ has flung the door of mercy wide open, and stands in the door calling and crying with a loud voice to poor sinners; a day wherein many are flocking to him…many that were very lately in the same miserable condition that you are in, are in now an happy state, with their hearts filled with love to him that has loved them and washed them from their sins in his own blood, and rejoicing in hope of the glory of God.” 
Edwards desires to awaken his congregants from (what he perceives to be) their blindness, pride, and darkness, to see that Jesus Christ is what we need. Jesus is the only One who can rescue us from the impending wrath of an incensed God. 
Edwards speaks terrifying words. He also speaks words of hope, but does so urgently, knowing we could die at any moment and forever be banished from God’s presence and plunged into eternal wrath and damnation. Once we die, it is too late. 
In John 14:6, Jesus says, “I am the way, and the truth, and the Life; no one comes to the Father but through Me” (NASB).
Edwards desperately wants us to see that Christ is the only salvation from this terrible fate, and he hopes we will be driven to Christ once we hear Edwards describe the wrath of God and our hopeless state.
You can read his whole sermon here.