The sermon's tone is didactic—in other words, it seeks to teach a lesson. It allows no space for questioning or disagreement, and it directly scolds the audience for failings which it assumes they have committed. It lays out the "correct" theological beliefs plainly and disproves incorrect ones.
The sermon is also a warning, both tonally and literally. The audience is in grave, immediate danger and must purify their soul as soon as possible. Edwards's urgent insistence is a persuasive tactic, but he also truly believed that souls would go to hell if they had not turned to Christ. In his eyes, this opportunity may be the audience's only chance to escape a danger they do not know they are in, and he speaks accordingly.
Edwards often sounds angry or frustrated with his audience in this sermon. Given the self-inflicted danger he believes they are in, this is no surprise. Like a parent scolding a child for doing something dangerous, Edwards wants to incentivize his audience to change their ways by any means necessary. Edwards refers to his listeners directly (take note when he uses the second person pronoun "you") and castigates them for their unwillingness to accept Jesus. He vividly describes his listeners hanging over the pit of hell, a rhetorical choice which heightens their fear.
But while the sermon seems quite pessimistic, readers should also notice the glimmer of hope Edwards provides, especially toward the end. He describes Christ as a merciful, loving, and accepting savior who will embrace sinners if they believe in him:
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, and pressing into the kingdom of God; [...] many that were very lately in the same miserable condition that you are in, are now in 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.
While Edwards leverages this optimism into further dire warnings for the unrepentant, his sermon is suffused throughout with the optimistic belief that there is, in fact, a sure way to avoid hell and be saved: by turning to Jesus. Jesus loves sinners and can remove even the greatest of sins through his sacrifice on the cross. Edwards takes on a hopeful tone whenever he speaks about Jesus and the possibility of salvation in this sermon.