If I were an orthodox Puritan, the sermon, which went on for hours, would both unsettle me and deepen my faith. An orthodox believer would worry that he/she might not be of the "elect" and predestined for heaven. Puritan faith created insecurity in its adherents, and they would constantly search themselves for signs that indicated whether they would be saved or damned. However, if I were living my faith in demonstrable ways that the dogma prescribed, I would feel that Edwards's words were inspirational and leading me to stay on the path of righteousness to avoid the horrors of hell that he so graphically described.
However, if I were more of a nominal Puritan, which was increasingly true of New Englanders in 1741, Edwards's sermon might lead me to think it was time to look for a religion that offered more reassurance than fear. Also, when Edwards changes his tone near the end of the sermon to tell his listeners that there was a small window of opportunity for people to change their ways, what he is saying defies Puritan orthodoxy. Puritanism's core tenet was that either people were, or were not, destined for heaven at birth, and to claim that people could earn their way to salvation would sound jarring. This shift in message might be another reason to send me in search of a religion that remained consistent in its teaching.