The tone changes drastically in the last paragraphs of the sermon. Why? What intent/function does this have?
After the Salem Witchcraft Trials, Puritanism waned significantly; therefore, revivalist preachers sought to re-engage Puritans by addressing their intellects and emotions both in order to convince their listeners of the gravity of their sins, and in order to prompt them to seek salvation and escape the punishment that a righteous God would wreak upon them.
When a rather recalcitrant congregation in Enfield, Conneticut, seemed untouched by the revivalist preachers, Jonathan Edwards, the greatest of the Revivalists, was therefore invited to preach before this congregation. He delivered his fire-and-brimstone sermon on July 8, 1741, at the height of what has been called the Great Awakening.
This sermon is in three parts, thematically based upon Deuteronomy 32:35: "Their foot shall slide in due time," a line from a long passage enunciating the wrath of God over the unfaithfulness and perversity of the Israelites. In the first part, Edwards speaks of the terrifying power of God, illustrating this with forceful metaphor and frightening imagery. In the second part, Edwards stresses that only a person's faith in God will hold them from the fiery pits of hell.
Then, in the third part, the tone changes as Edwards directly addresses the congregation of Enfield before him, switching from third person to second person:
The use of this awful subject may be for awakening unconverted persons in this congregation. This that you have heard is the case of every one of you that are out of Christ....
Your wickedness makes you as it were heavy as lead, and to tend downward with great weight and pressure toward hell; and if God should let you go, you would immediately sink and swiftly descend and plunge into the bottomless gulf...and your own care and prudence, and...all your righteousness, would have no more influence to uphold you and keep you out of hell, than a spider's web would have to stop a fallen rock....
In this address rife with frightening images and powerful metaphors, Edwards speaks to those who have convinced themselves that because of their religiosity, their moral behavior, and their church attendance they are saved, informing them that they are yet in danger. Their vain rationalization will not save them; only the grace of God can do this. "Now God stands ready to pity you....“hearken to the loud calls of God’s word and providence” he urges.