Hyperbole, or exageration, as he is angry and trying to depict an image of the nature of man which is basically evil, and worthy of punishment and pain. He also uses hyperbole to actively describe the cause and effect of the ruin of man.
He uses social engineering, or the gathering of fake data to comply with what people need to hear and convince them to do what he wants them to do. I am not saying what he was saying was totally fake, that is up to his belief system, but certainly the manner in which he is decidedly willing to feed them this information about who we are, and what they are doing, and about how bad it is to deviate from his ways, is deceptive to a point, and geared to proving his point right.
Without knowing it, he is using the classical Monroe Motivated Sequence of persuasion which consists on:
Grabbing the Attention- If he hadn't he wouldn't have had an audience.
Trigger the need of the listener (the fact that, according to Edwards their ways will send them to hell)
Proposing a way for them to not go and burn due their actions (by changing their ways)
Visualization of an objective (in this case, he let them visualize themselves as the title states "in the hands of an Angry God" and about to be dumped in the burning flames of Hades.
Action: When he is done telling them all that they will suffer, he subtlely suggests a change of hearts and behaviors, so that they sinners can be saved.