Which of Jonathan Edwards's Works Represents His Greatest Contribution to American Religion?

After reading the various writings of Jonathan Edwards for my upcoming fall 2013 course on "Jonathan Edwards's Life, Thought, and Legacy in American Religious Culture," I am struck by the question: Which of Edwards's works represents his great contribution to American religion?

His Faithful Narrative and Life of Brainerd are among his best-selling works, but what about his less popular writings that have made more of a theological contribution to religion, including his early work, A Divine and Supernatural Light as well as later books such as his Treatise Concerning Religious Affections, Original Sin, and Freedom of the Will? One must also consider his posthumous works, including The Nature of True Virtue and his masterpiece, A History of the Work of Redemption. Furthermore, there are the spiritual gems in his "Miscellanies" to take into account.

With so many interesting writings to mull over, it is no wonder that Edwards has been called "America's Theologian."