While spending the night at Wuthering Heights, Lockwood peruses the titles of some old religious books next to his bed and proceeds to dream about one of the authors, a preacher named Jabes Branderham. The dream (really a nightmare) is a satire of lengthy sermons by English Nonconforming ministers:
However, in my dream, Jabes had a full and attentive congregation: and he preached—good God—what a sermon! divided into four hundred and ninety parts—each fully equal to an ordinary address from the pulpit—and each discussing a separate sin! Where he searched for them, I cannot tell; he had his private manner of interpreting the phrase, and it seemed necessary the brother should sin different sins on every occasion.
The title of Branderham's actual sermon is "Seventy Times Seven, and the First of the Seventy First." The title alludes to a passage in the Gospel of Matthew, where Peter asks Jesus how often we should forgive "a brother" who sins against us—up to seven times? Jesus replies that we should rather forgive "seventy times seven" times, a clear hyperbole meaning that Christians should always be willing to forgive. In Lockwood's dream, however, Branderham takes the "seventy times seven" literally, dividing his sermon on the subject into 490 sermon-length sections—meaning that Lockwood is nightmarishly cursed to listen to 490 consecutive sermons. Not only that, but Branderham devotes each sermon to a different kind of sin.
Brontë expects her audience to find Lockwood's dream funny because of its satirical take on real-life sermons by English Nonconforming preachers. "Nonconformist" simply refers to Protestants who weren't part of the officially established Church of England (Anglican)—groups like Methodists, Baptists, and Quakers, among others. By the time Wuthering Heights was published in 1847, there were more Nonconformist chapels and meetinghouses than Church of England churches in England. (Also, note that Brontë's father was an Anglican curate.) Nonconforming ministers were often known for their lengthy sermons, which were broken into minute divisions—though Branderham's 490-part discourse is pure exaggeration. Branderham's insistence on delineating 490 distinct sins is also a satiric reference to some Nonconforming preachers' idiosyncratic interpretations of the Bible, and perhaps especially to their tendency to come up with more and more kinds of sin to preach against.
Though Nonconformist sermons, both written and preached, were very popular, plenty of drowsy listeners no doubt wished they could respond as Lockwood ultimately does in the dream—by exploding with frustration at the tireless preacher. Though this satirical dream doesn't serve much of a narrative purpose beyond setting up Lockwood's next nightmare, it is probably meant to give readers a good laugh and a moment of levity before the story takes a darker, more Gothic turn.
Nelly describes Joseph, lifelong servant at Wuthering Heights, as a "Pharisee," alluding to the religious leaders who hated, challenged, and conspired against Jesus in the gospels.
He was, and is yet, most likely, the wearisomest, self-righteous pharisee that ever ransacked a Bible to rake the promises to himself, and fling the curses on his neighbours.
Colloquially, a "Pharisee" is any religious person who's conspicuously self-righteous and judgmental. In the gospels, it's not the Pharisees' religiosity that Jesus criticizes, but their tendency to interpret the Scriptures in ways that flattered themselves and to appear as religious as possible in front of others, while condemning those who didn't meet their artificial standards. Similarly, Nelly herself appears to be a fairly devout Christian, so it's not Joseph's religion in itself she objects to, but his attitude about it. He's fond of "sermonizing" at length, typically at the expense of those within earshot. In particular, when Nelly says that Joseph "[rakes] the promises to himself and [flings] the curses" on others, she refers to the way Joseph (mis)uses the Bible, assuming that all of God's promises of blessing must apply to him without considering that any of God's curses on the sinful and proud could possibly apply to him—only to others. In short, Joseph is a hypocrite whose showy, self-righteous piety makes life miserable for everyone around him.
In Chapter 9, Catherine talks to Nelly about how she could never forsake Heathcliff, even though she can't marry him. In doing so, she alludes to the story of the ancient Greek wrestler Milo of Croton:
‘He quite deserted! we separated!’ she exclaimed, with an accent of indignation. ‘Who is to separate us, pray? They’ll meet the fate of Milo! Not as long as I live, Ellen—for no mortal creature. Every Linton on the face of the earth might melt into nothing, before I could consent to forsake Heathcliff.'
The historical Milo was a six-time Olympic champion who lived in the sixth century B.C.E. As legend has it, he decided to test his strength one day by trying to tear a tree apart with his bare hands, but then his hands got trapped inside the trunk and he was devoured to death by wild animals. So, Catherine is saying that if anyone tried to force her and Heathcliff apart, they would not only be thwarted in the attempt, but would suffer gruesomely for trying. This startlingly violent allusion illustrates Catherine's fervent passion for Heathcliff (and also suggests that it's a naively youthful, not terribly rational passion).
As a side note, Catherine's use of this allusion indicates that she's fairly well educated—she has enough familiarity with classical legends that she can readily appeal to them in everyday speech. Ironically, this shows that, in terms of class, she has more in common with the Lintons than with Heathcliff.
After a lightning bolt strikes Wuthering Heights on the night Heathcliff runs away, Joseph and Nelly both react with allusions to biblical patriarchs and prophets:
We thought a bolt had fallen in the middle of us, and Joseph swung onto his knees, beseeching the Lord to remember the Patriarchs Noah and Lot; and, as in former times, spare the righteous, though he smote the ungodly. I felt some sentiment that it must be a judgment on us also. The Jonah, in my mind, was Mr Earnshaw, and I shook the handle of his den that I might ascertain if he were yet living.
Joseph assumes that the lightning bolt is a sign of God's judgment on Wuthering Heights. In typical Joseph fashion, however, he jumps to the conclusion that God is "[smiting] the ungodly" but might be persuaded to "spare the righteous" (presumably including Joseph himself). In doing so, he begs God to act as he did in the days of the patriarch Noah (when God wiped out humanity with a deadly flood but spared righteous Noah and his family) and Lot (whose town of Sodom was destroyed for its notorious wickedness while Lot's family was permitted to flee). The subtle irony here is that the biblical narrative presents both Noah and Lot as truly virtuous men; Joseph, on the other hand, has already been established as a contemptible hypocrite.
Nelly, for her part, thinks the divine judgment idea could be legitimate, but she finds a different culprit—Hindley Earnshaw, who has been tormenting his adopted brother Heathcliff for years and earlier that very day had threatened his little son Hareton's life in a drunken fit. Nelly also chooses a different Bible reference—Jonah, who ran away on a ship when God called him to be a prophet; when God sent a perilous storm in response, the sailors figured out Jonah was to blame and flung him overboard. Nelly likens the drunken Hindley to Jonah, suggesting that the reasons for Wuthering Heights's suffering can all be traced back to Hindley's wrongdoing. Nelly's allusion is a bit tongue-in-cheek; and yet, while Joseph just uses the opportunity to loudly trumpet his own righteousness, Nelly takes the responsibility to at least try to confront the supposed wrongdoer. Assuming a high level of biblical literacy in her audience, Brontë sprinkles such allusions into her characters' speech without feeling the need to provide further context.
After Catherine dies, Isabella tells Nelly how Heathcliff has been behaving in his mad grief, ironically likening Heathcliff to a pious Christian:
There he has continued, praying like a methodist; only the deity he implored is senseless dust and ashes; and God, when addressed, was curiously confounded with his own black father! After concluding these precious orisons—and they lasted generally till he grew hoarse, and his voice was strangled in his throat—he would be off again; always straight down to the Grange!
Isabella recently married Heathcliff and has suffered from his abuse, telling Nelly earlier that she doesn't regard him as human. Here, she ironically twists the simile "praying like a methodist" around by alluding to Satan and suggesting that, far from being a prayerful, sympathetic mourner, Heathcliff is a monster and damned.
The Protestant religious movement known as Methodism had only become widespread in England by the mid-1700s; at this point in the story's timeline (the 1780s), "Methodist" was a broad-brush term that could be used to apply to anyone who was fervent in their religious practice, especially in enthusiastic prayer. But Isabella doesn't mean the term at all literally, as her next comments show.
The "deity" of "senseless dust and ashes" refers to the late Catherine. In other words, Heathcliff isn't even praying fervently to God, but to the spirit of his dead beloved. Further, "his own black father" refers to the devil, with whom Heathcliff, in his grief and rage, blasphemously conflates God (and Isabella calls Heathcliff the devil's offspring). The fact that Heathcliff's desperate "prayers" are a mashup of pleading and curses (none of which are directed to God) demonstrates that he is utterly irreligious. Like "methodist," then, "precious orisons" (or prayers) is verbal irony, sarcastically characterizing Heathcliff's blasphemous ravings as sincere piety.
One day, Heathcliff encounters Cathy outside the walls of the Grange and gives her a hard time for no longer writing to Linton (at Nelly's insistence). Heathcliff alludes to the Slough of Despond in John Bunyan's The Pilgrim's Progress to indicate how unhappy Cathy's neglect has made Linton:
I presume you grew weary of the amusement, and dropped it, didn’t you? Well, you dropped Linton with it, into a Slough of Despond.
Early in The Pilgrim's Progress, the allegorical protagonist, Christian, gets stuck in the Slough of Despond, a miry bog symbolizing the obstacles a Christian encounters in the quest for holiness, and almost sinks as he sets out on his journey toward the Celestial City. Heathcliff's allusion is much simpler—he just means that Cathy's failure to write to Linton has caused Linton to get depressed, as if he's sinking in the Slough.
However, the matter-of-fact allusion to Bunyan's religious classic is interesting in itself. It's hard to overstate how popular The Pilgrim's Progress was, in England and around the world, from the time of its publication in the late 17th century through the Victorian era. Next to the Bible, it was one of the bestselling books of all time, and even if a household didn't own a copy, most people would have been familiar with the major characters and plot points. This is pointedly clear when even godless Heathcliff can make an off-the-cuff reference to the book!
Moreover, the reference to the Slough of Despond would be familiar to Cathy and concisely get across how miserable Linton is, making her feel guilty—which is precisely Heathcliff's cruel intent.
While detaining Nelly and Cathy at Wuthering Heights, Heathcliff has been talking about his son Linton's capacity for selfishness and cruelty, and Nelly responds by calling Linton a "cockatrice," a mythical creature:
‘You’re right there!’ I said, ‘explain your son’s character. Show his resemblance to yourself; and then, I hope, Miss Cathy will think twice, before she takes the cockatrice!’
A cockatrice is a two-legged, serpent- or dragon-like creature with a rooster's head. It had the ability to kill someone just by looking at them. A cockatrice-like creature is described in ancient natural histories and medieval bestiaries, but its usage in English probably came by way of the enormously popular King James translation of the Bible. The King James Version uses "cockatrice" to translate the Hebrew word for a serpent-like creature in Psalm 91, Proverbs 23, and several chapters of Isaiah. Cockatrices also showed up a lot in Elizabethan drama, like Shakespeare's Richard III and Romeo and Juliet.
With the cockatrice allusion, Nelly is suggesting that Linton, like his father Heathcliff, is more beast than human. He may be physically weak, but he is deceptively cruel. As such, he has the potential to ruin Cathy, if only through emotional torment and tyranny. Cathy is willing to do what Heathcliff wants and marry Linton so that she'll be allowed to return to her dying father's bedside, but Nelly hopes that if Cathy understands Linton's resemblance to his monstrous father, she'll reconsider.