Answer:
The narrator's tone is elevated. Because it's not meant to make people feel better, but to tell them what will happen if they don't change their ways and follow God's rules. He wants to make his readers and listeners afraid and dreadful, but he also wants them to want to stop doing bad things and change their lives. He speaks directly to the congregation at times, which adds authenticity and relevance to the sermon's ideas.
"They were always exposed to Destruction, as one that stands or walks in slippery Places is always exposed to fall" - simile, or comparison of two actions using the preposition "like" or "as" "What are we, that we should think to stand before him, at whose Rebuke the Earth trembles, and before whom the Rocks are thrown down?" - a rhetorical question that doesn't require an answer because the answer is self-evident. To put it another way, we are nothing.
"The Sword of divine Justice" - a metaphor that represents something else. In this instance, the Sword of divine Justice symbolizes God's wrath, which may be cruel to sinners but is necessary for his justice.
"The Pit is prepared, the Fire is made ready, the Furnace is now hot, ready to receive them, the Flames do now rage and glow" - visual and tactile imagery. Even though he's discussing moral concepts like sin and punishment, his use of imagery like a blazing Hell can transport listeners to another world entirely.
These elements may have created a fearful atmosphere in the audience. As sinners, we all have a sense of dread and fear, which they help to evoke in the reader.
I hope this helps you
:)