Jonathan Edwards' sermon is based on Puritan dcotrine, which in turn is based on John Calvin's theology (the kind of philosophy deal with religion), and that in turn is based on the philosophy of St Thomas Aquinas. The starting point is: because of the sin of Adam and Eve (in Genisis) the human race is "fallen," is corrupt by nature. All humans are born with the stain of Original Sin (the sin of Adam and Eve's disobedience). Edwards preaches that we all deserve eternal damnation, eternity in Hell, because our nature is inseparable from sin.
God knows all things and we can do nothing to save ourselves. We are worms beneath the feet of Almighty God. Despite this, God takes a few of us, His Elect, into Heaven. God has known since the beginning of time who would be saved and who would be damned; therefore our lives, our actions, are Predestined. We have no free will. That is another part of Edwards' philosophy. Whether we believe in Christ, Whether we live holy lives--these things have been determined for us by God since the beginning of time.
No one may question God's "justice" and no one may "earn" God's Grace. We are unworthy.