Calvinism
The overarching theme of the sermons of Edwards and fundamental to his entire theological philosophy is the Calvinist doctrine of man’s helplessness in determining his own salvation. God is the all-powerful sovereign whose grace alone ensures the possibility of salvation and the exercise of that grace can instantly nullify a lifetime of good works. Faith in this concept as an unavoidable truth informs every other thematic concern touched upon in the sermons of Edwards.
Free Will in the Passive Voice
Edwards believed that humans were given free will by God, but that it can only be exercised as a passive reaction to the external forces of God. Human nature is constructed to accept and be moved by positive motives and likewise be repelled from action by negative motives. Since all motives—both positive and negative—exist only as manifestations of God’s providence, any exercise of will is necessitated by the intervention of God. God is the author and man is the actor in the playing out of a willful determination.
The Depravity of Mankind
Underlying the message of Calvinist doctrine that God’s grace alone determines salvation is the theme of innate depravity and wickedness of the human race. Edwards rejects the idea that man has a natural inclination toward virtue and that truly virtuous acts are rare. Instead, he pinpoints Original Sin and the fall of Adam and Eve from paradise as the engineering principle of a psychological wired to be selfish in determination of motive and self-interested in the machinations for consequence. Hence, grace from God becomes a necessity for salvation since man is in no position to rely upon the goodness of his acts to quality him for eternal paradise.