Before the Great Awakening, most of the religious Americans believed they were predestined by God for Hell or Heaven. Therefore, they cared less about what their acts towards God may bring when they die. However, promoters of the Great Awakening did not agree and believed if every individual loves God and accepts his love, they could save themselves from the cruel suffering.
Jonathan, through his sermon, wanted to persuade people to believe and love God, as well as accept the love that God returns, so as to stay away from Hell. He warns individuals about the dangers in Hell and says- to improve their chances of going to Heaven, they must devote their true believes towards God and his mercy.