The book uses Christian conversion and salvation narratives as a metaphor for English ethnic identity and belonging. For example, in Volume 1, Book 5, Chapter 10, Priamus injures Gawaine with a magically enhanced weapon, then promises to heal him if only Gawaine will "christen" him:
‘That may I do,’ said the knight, ‘if I will, and so will I if thou wilt succour and aid me, that I may be christened and believe on God, and thereof I require thee of thy manhood, and it shall be great merit for thy soul.’
Priamus is not a baptized Christian when he meets Gawaine. It seems odd that he is so desperate to be baptized ("christened"); this is the one favor he asks of Gawaine when he could ask him for anything. But in the context of Le Morte d'Arthur, seemingly everyone wants to be a baptized Christian. In Volume 2, Book 12, Chapter 14, Tristram tells Palomides that God will forgive "all thine evil" if he surrenders his "Saracen," or Muslim, identity and becomes a Christian:
‘Now take your horse,’ said Sir Tristram, ‘and as ye say so it shall be, and all thine evil will God forgive it you, and I do. And here within this mile is the suffragan of Carlisle that shall give you the sacrament of baptism.’
Then they took their horses and Sir Galleron rode with them. And when they came to the suffragan Sir Tristram told him their desire. Then the suffragan let fill a great vessel with water, and when he had hallowed it he then confessed clean Sir Palomides, and Sir Tristram and Sir Galleron were his godfathers.
In the cases of both Priamus and Palomides, converting to Christianity helps them mend rifts with Arthur's knights and join forces with this brotherhood of knights. This is especially evident in the case of Palomides, who gets two "godfathers" out of the deal. Giving up his Muslim identity and embracing Christianity helps him form religious kinship ties that were previously unavailable to him.
The literal justification in the text for the pressure on non-Christians to convert is that Christianity leads to God's forgiveness and a place in heaven. Like Galahad and Launcelot, Palomides and Priamus are offered the chance to be lifted to heaven by angels. On a metaphorical level, though, Palomides and Priamus's conversions reinforce Christianity as the tie binding together Arthur's knights, and by extension England. In the 15th century, when Malory was writing, England's politics and borders were unstable. The monarchy was still very much mixed up with feudalism, and different families jockeyed for power. Still, there was a longstanding tradition among many of these families of treating non-Christians (Muslims, Jews, and others) as outsiders. As different political factions fought over where and how to consolidate power, English ethnic identity and belonging hinged largely on Christianity and its perceived superiority to other religions. Myths about King Arthur helped prop up the idea that Christianity had deep and sacred roots in England. The book's celebratory narratives about Christian conversion and salvation generally represent the idea that a "real" English person can prove their English-ness with their Christianity, and that all "real" English people are destined to go to heaven.
The book uses Christian conversion and salvation narratives as a metaphor for English ethnic identity and belonging. For example, in Volume 1, Book 5, Chapter 10, Priamus injures Gawaine with a magically enhanced weapon, then promises to heal him if only Gawaine will "christen" him:
‘That may I do,’ said the knight, ‘if I will, and so will I if thou wilt succour and aid me, that I may be christened and believe on God, and thereof I require thee of thy manhood, and it shall be great merit for thy soul.’
Priamus is not a baptized Christian when he meets Gawaine. It seems odd that he is so desperate to be baptized ("christened"); this is the one favor he asks of Gawaine when he could ask him for anything. But in the context of Le Morte d'Arthur, seemingly everyone wants to be a baptized Christian. In Volume 2, Book 12, Chapter 14, Tristram tells Palomides that God will forgive "all thine evil" if he surrenders his "Saracen," or Muslim, identity and becomes a Christian:
‘Now take your horse,’ said Sir Tristram, ‘and as ye say so it shall be, and all thine evil will God forgive it you, and I do. And here within this mile is the suffragan of Carlisle that shall give you the sacrament of baptism.’
Then they took their horses and Sir Galleron rode with them. And when they came to the suffragan Sir Tristram told him their desire. Then the suffragan let fill a great vessel with water, and when he had hallowed it he then confessed clean Sir Palomides, and Sir Tristram and Sir Galleron were his godfathers.
In the cases of both Priamus and Palomides, converting to Christianity helps them mend rifts with Arthur's knights and join forces with this brotherhood of knights. This is especially evident in the case of Palomides, who gets two "godfathers" out of the deal. Giving up his Muslim identity and embracing Christianity helps him form religious kinship ties that were previously unavailable to him.
The literal justification in the text for the pressure on non-Christians to convert is that Christianity leads to God's forgiveness and a place in heaven. Like Galahad and Launcelot, Palomides and Priamus are offered the chance to be lifted to heaven by angels. On a metaphorical level, though, Palomides and Priamus's conversions reinforce Christianity as the tie binding together Arthur's knights, and by extension England. In the 15th century, when Malory was writing, England's politics and borders were unstable. The monarchy was still very much mixed up with feudalism, and different families jockeyed for power. Still, there was a longstanding tradition among many of these families of treating non-Christians (Muslims, Jews, and others) as outsiders. As different political factions fought over where and how to consolidate power, English ethnic identity and belonging hinged largely on Christianity and its perceived superiority to other religions. Myths about King Arthur helped prop up the idea that Christianity had deep and sacred roots in England. The book's celebratory narratives about Christian conversion and salvation generally represent the idea that a "real" English person can prove their English-ness with their Christianity, and that all "real" English people are destined to go to heaven.
In Volume 2, Book 14, Chapter 2, the Queen of the Waste Lands tells Percivale about how Merlin made the Round Table and informed the men about the future of the Grail quest. Merlin's prophecy reportedly involved a great deal of figurative language, including a metaphor and a pair of similes:
And men asked him how men might know them that should best do and to achieve the Sangrail. Then he said there should be three white bulls that should achieve it, and the two should be maidens, and the third should be chaste. And that one of the three should pass his father as much as the lion passeth the leopard, both of strength and hardiness.
The three white bulls (two maidens and one chaste) are a metaphor for the people who will find the grail (Percivale, Sir Bors, and Galahad). But this metaphor has multiple layers. White is usually associated with good and with devout Christianity in Malory's book. The white bulls themselves could represent any knights, as long as they are aligned with good and with God, and as long as one of them is "chaste."
The first real clue to who these three will be lies in the metaphorical comparison between "white bulls" and "maidens." Bulls are male, but the prophecy describes two of them as "maidens" (a feminine term). Maidens are women who have never been married, which should mean (according to the conventions of Arthur's court and Malory's day) that they have never had sex. There is no equivalent term for men because the same standard does not apply to them, so Merlin simply uses a metaphor to compare two of the "white bulls" (or good knights) to "maidens." A "maiden" knight is in fact so special that this status is part of what qualifies him to achieve the Sangreal. By the time Galahad and Percivale reach the Sangreal, they are the only two knights who qualify. It is notable that Sir Bors also qualifies to "achieve" the Sangreal even though he is merely "chaste," not strictly virginal. This means he has given into sexual temptation once but that it doesn't count against him enough to disqualify him. Just as Launcelot is lax and hypocritical about his own definition of fidelity, the book gives Sir Bors leeway that is rarely if ever offered to women.
The second clue that Galahad in particular will reach the Sangreal lies in the analogy claiming that one of the "white bulls" will surpass his father like a lion surpasses a leopard. The central father and son duo is Launcelot and Galahad, so this is a fairly clear indicator that Galahad will prevail. This analogy is a three-part simile. Merlin compares the relationship between the father and son in question to the relationship between a leopard and a lion. Within that comparison, he compares Launcelot to a leopard and Galahad to a lion. The lion comes up again and again in the book as a symbol of Christ, and Galahad's achievement of the Sangreal makes him a Christ-like figure. It is a flattering comparison. By contrast, Merlin compares Launcelot to a leopard. The leopard may be powerful and fast, but it cannot quite compete with the lion. This is the tragedy of Launcelot's character: he is extremely powerful and very good, but he is not a match for Galahad. However, he gets some redemption at the end of the book, when he is carried to heaven just as Galahad was.
In Volume 2, Book 17, Chapter 2, Galahad, Sir Bors, Percivale, and a woman who turns out to be Percivale's sister all find an empty ship. Letters they find at the back of the ship use a metaphor to personify the concept of faith:
Thou man, which shall enter into this ship, beware thou be in steadfast belief, for I am Faith, and therefore beware how thou enterest, for and thou fail I shall not help thee.
This ship is faith, and if the knights are not faithful, the ship will be wrecked. The idea that a ship can symbolize faith comes from the Bible, in which the apostle Paul tells Timothy that people who have lost their faith are spiritually shipwrecked. Paul's representation of faith as a ship is a metaphor, not personification. Malory is using this metaphor, but he also allows the ship, "Faith," to speak for itself. Personified, it promises to keep the knights afloat in exchange for their "steadfast belief."
By personifying Faith in this way, Malory emphasizes that these knights have an obligation to their faith just as they have an obligation to Arthur or to one another. Their covenant with Faith is what will keep them afloat as they try to reach the Sangreal. Breaking their promises to Faith may or may not kill them, but it will certainly end their journey toward the Sangreal, which requires moral purity to be achieved. By turning the ship of faith into a literal ship with which the knights have a contract, Malory emphasizes their physical journey to the Sangreal as an allegory for the spiritual journey to prove themselves worthy for heaven. If they fail in one of these journeys, they will fail in the other.
In Volume 2, Book 20, Chapter 5, Launcelot explains to several of his supporters that he has accidentally killed Agravaine and at least 12 other knights. He uses a metaphor to describe the dire circumstances they are all in:
[...]these knights were sent and ordained by King Arthur to betray me. And therefore the king will in this heat and malice judge the queen to the fire, and that may not I suffer, that she should be burnt for my sake [...]
Launcelot is saying that Arthur is going to burn Guenever at the stake so that he does not have to turn against Launcelot. Launcelot refers to Arthur's anger metaphorically as "heat." The implication in the context of this passage is that Arthur is already burning emotionally just as Guenever is soon to burn physically. Arthur is in such a state of torment that he must choose between exacting revenge on his best knight or on his wife. The fact that Arthur chooses to turn his burning anger on Guenever (literally) demonstrates the deep misogyny of Malory's book. More than this, it emphasizes just how deep the bond between men runs in the social order the book venerates. Under the chivalric code, it is worse for Arthur to murder his best knight than it is for him to murder his wife. Of course, things soon devolve past the point where Arthur and Launcelot's relationship can be saved. But in this moment, it seems that Arthur really thinks his anger will burn out with Guenever's body. She is being thrown on a sacrificial fire so that Arthur can keep loving Launcelot.