Robinson Crusoe is replete with biblical allusions. The main character compares his experiences, and particularly his struggles, with those of figures from the Bible. In addition, Robinson evidently sees himself as belonging to a lineage of important men who have been guided by God, punished by God, and who have withstood God's trials. Besides the allusion to Jonah, Defoe also alludes to Solomon, the Prodigal Son, Abraham, Elijah, Saul, and Job. He also actively quotes or paraphrases key passages from the Bible, taking from Psalms, Acts, John, Joshua, Hebrews, Romans, Matthew, Exodus, and more. Robinson additionally refers to the Book of Common Prayer.
These citations of the Bible and allusions to biblical figures are central for Robinson's proselytizing goals as a narrator. He claims that he spent much of his time on the island reading the Bible he had found on the ship. Robinson's ability to invoke the Bible at every turn gives him credibility as a religious man.
The allusions also shed light on Defoe as an author. Like Robinson in his role as narrator, Defoe becomes a credible author on account of his biblical citations—the reader trusts him because he proves himself to be a well-read man of religion. It is Defoe himself who tells readers to look for Christianity in his work and who sets himself up to be judged by readers for the piety of his writing. In the preface, he emphasizes that the story is told "with a religious application of events to the uses to which wise men always apply them." It is thus important for Defoe to underline his knowledge of the Bible, which he does by continuously applying it to his story. By way of these allusions, he seeks to emphasize that he is devout both as a man and as a writer, and that his story can have instructive value for a Christian reader.
In Chapter 2, Robinson sets off on a voyage and experiences his two first storms as a sailor. The first storm seems to make an impression on no one but Robinson himself, and the other sailors mock his naiveté when he reveals that it frightened him. The second storm, however, frightens everyone on board; even the weathered Shipmaster prays to God for assistance, certain that they "shall be all lost, [...] all undone."
When they make it back to shore instead of foundering, the Shipmaster finds out that Robinson had considered this voyage as a trial. This discovery enrages the Shipmaster, who tells Robinson to go back home and prophecies that he will face great calamities if he continues on his seafaring adventure. Alluding to Jonah, he suggests that their near-death experience was Robinson's fault.
Young man, [...] you ought never to go to sea any more, you ought to take this as a plain and visible token that you are not to be a seafaring man [...] as you made this voyage for a trial, you see what a taste Heaven has given you of what you are to expect if you persist; perhaps this is all befallen us on your account, like Jonah in the Ship of Tarshish.
The severity of the Shipmaster's accusation is heightened by the comparison of Robinson to Jonah. In the Old Testament, God sends a storm after Jonah when Jonah runs away from what God had asked him to do. Just as Robinson gets on the Shipmaster's ship to flee the life his father wants for him, Jonah gets on a ship to flee from God's wishes. The Shipmaster finds Robinson's unfilial decision-making as inauspicious as Jonah's disobedience to God and suggests that Robinson's presence on his ship was the reason for the tempest.
This allusion can also be understood as a form of foreshadowing. Jonah is eventually thrown into the sea, just as Robinson eventually ends up in the shipwreck. To save Jonah from drowning, God sends a large fish to swallow him up. Although Robinson does not find himself swallowed by a fish, he does come to believe that God saved him. The fish that God sent to swallow Jonah returns him to dry land; in Robinson's view, it was God who ensured that he survived the shipwreck and made it to the island. Jonah and Robinson end up in the sea because of their own foolishness and disobedience, and they both attribute their survival to divine providence.
In Chapter 3, following his escape from Morocco, Robinson comes across a lion. With the help of Xury, he clumsily but successfully slays the great beast and takes its skin. This episode is an allusion to the Greek hero Hercules and his slaying of the Nemean Lion.
In the story, seeking to atone for a bout of madness that caused him to kill his own wife and children, Hercules goes to serve King Eurystheus. This king sends Hercules off to undertake a series of seemingly impossible tasks, known as the labors. His first labor is to slay the Nemean lion, whose skin is resistant to weapons. Hercules finally succeeds in slaying the Nemean Lion by strangling it. After his armor is destroyed by the lion, the hero assumes the lion's weapon-resistant skin as his armor. Hercules can be identified on Greek vases by this unique accessory.
"I took the best aim I could with the first piece to have shot him into the head, but he lay so with his leg rais’d a little above his nose, that the slugs hit his leg about the knee, and broke the bone. He started up growling at first, but finding his leg broke fell down again, and then got up upon three legs and gave the most hideous roar that ever I heard."
Just as Hercules confronts a lion at the start of his life of labors, Robinson confronts a lion at the start of his life of adventures. Robinson is no Hercules, however. He is much clumsier and much more fearful, and thereby more realistic—a hero of his own era. Unlike Hercules, for example, Robinson does not strangle the lion. In fact, he cannot even claim to be the one who finally kills it, as it is Xury who kills the lion after neither of Robinson's two shots succeed in killing it. Once the lion is dead, the man and the boy remove and keep the lion's skin, just like Hercules.
"Indeed it took us both the whole day, but at last we got off the hide of him, and spreading it on the top of our cabin, the sun effectually dried it in two days time, and it afterwards serv'd me to lye upon."
Rather than keeping the skin as a token of his great heroism, Robinson keeps the skin because he recognizes its utility. He does not use it as armor, but for shelter, warmth, and comfort. And down the line, he sells the skin to the Portuguese captain who saves him. This detail, that the skin is given further value through a financial transaction, is a crucial historical marker. Defoe may be alluding to Hercules's first labor with the slaying of the lion, but he very much embeds the lion episode and its aftermath within the story's specific historical context. In this period of flourishing mercantilism—and early capitalism—the ultimate purpose of Robinson's lion skin is profit.
The point of this allusion is not to suggest that Robinson is exactly like Hercules, as Robinson's heroism does not at all belong to the Greek Heroic Age. Throughout the novel, he is most of all a hero of pragmatism. That being said, although he is no herculean hero, Robinson does develop into a more daring figure with time (and with God's increasing presence in his life). He arrives on the island terrified and hopeless, but transforms into the colonial master of his microcosm.
