Stevenson didn't believe in God but he wrote about it because his readers would enjoy but he has a humorous tone underneath it all - making fun of his readers
"really likeSatan" ... "If I ever read Satan's signature uponaface, it is on that of your new friend" 1
Stevenson has done this to directly compare Hyde's behavior to Satan's.
This shows that Hyde is an abominable human being who doesn't really have a conscience.
This shocks the Victorian reader due to their religious beliefs and their knowledge and understanding of Satan's behavior and actions.
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Simile has religious connotations of hell. Comparing Hyde to Satan makes the audience think of evil, and sin. In a Victorian Era where society is strongly religious this shows that Hyde is to be despised as he is so wicked.
However it could also be said that the comparisonis in the power of the devil. In the Bible the devil seeks to destroy and tempt people to sin.
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The sibilancewhen Hyde is described as having'Satan'ssignature' makes the quote more ominous as it reminds the audience of the hiss of a snake/serpent which has connotations of the devil. It could also be a hiss of disgust
From a Biblical standpoint mankind was said to be Gods creation and the fact that Hyde has Satan's signature sets him apart from what is human and God's work another reminder of his evil character.
"I incline to Cain's Heresy"
Stevenson uses the story in the bible where Cain kills Abel and then says when asked by God where Abel is, Cain says "Am I my brother's keeper."
This is mirrored when Hyde kills Jekyll.
It basically shows that even though Utterson stays out of the attack, he is equally "innocent" as he is condemned because he allows bad things to happen and does not try to stop them