If Launcelot is the best of Arthur's knights on the battlefield, Galahad is his best Christian knight. His all-around awesomeness makes sense, given the fact that he's Launcelot's son, who is conceived when Launcelot is tricked into sleeping with Elayne of Corbin. This Elayne is the daughter of a family with a lineage stretching back to Joseph of Arimathea, the legendary keeper of the Holy Grail – the cup that Christ used at the Last Supper. Therefore, in Galahad, martial and religious devotion intermingle to create a perfect storm of a knight. He's good with a blade, and with a prayer.
Immediately after Galahad's conception, Elayne explains to Launcelot that she has agreed to sleep with him in order to fulfill a prophecy, and that she now bears in her womb "the moste nobelyste knyght of the worlde" (469.39-40). If that sounds like a tall order, well, it is. But her prediction totally comes true when a sword in a stone appears floating in the river at Camelot. Apparently, this sword can only be pulled by the best knight in the world. For the first time in his life, Launcelot fails at something only to be bested by his son, who pulls the sword easily.
So what makes Galahad the best knight in the world? It's not his skill on the battlefield. Sure, he defeats seven knights at once in the Castle of Maidens and single-handedly rescues a castle from an army. But we can't help thinking Launcelot could easily pull that stuff off.
No, Galahad's got something else going for him. Everything he's able to do occurs because of his devotion to God. And more important than his deeds of arms are the miracles Galahad performs, like exorcising a demon from a man, repairing a shattered sword with a single touch, or healing the so-called "Maimed King" with a spear. These miracles show that our Galahad is one with Christ, another miracle-performer.
Plus, there's the fact that he's a virgin. And in Arthur's day and age, that was a sure sign of Christian sanctity. Free from the touch of a woman, Galahad is able to see the Holy Grail, an achievement of which Launcelot falls short (no wonder). Galahad's virginity represents his separation from earthly, bodily things. He's not interested in the flesh, and he's not meant for this earth, which is probably why he doesn't remain on it long. After praying before the Holy Grail for an entire year – yep, a year – he asks God to take his soul. He doesn't, like so many of the other knights, die in battle. Instead, he dies in prayer.
Galahad's presence in Le Morte D'Arthur, along with Grail Quest plot line, marks a shift in the story. Before Galahad, the tales were all about chivalric deeds, battles, and jousting. But once Galahad comes along, and the knights begin their Grail Quest, Le Morte takes on a distinctly more spiritual focus. The attributes that make a knight spiritually successful – chastity, abandonment of bodily pleasures, devotion to God alone – are very different from those that make him successful on the battlefield. Yet Galahad excels in both arenas because he has God on his side, and he's on God's side, too.
This also means that he has a happier end than that of Arthur's more earthly knights (and that of Arthur himself, too). As the Round Table descends into feuding and chaos, envy and lust, Galahad's story is a reminder of the perfection that's possible for the knight who moves beyond such earthly concerns. True chivalry, it seems, is not about helping the ladies. It's about helping the man upstairs. And because he does just that, Galahad dies a peaceful, happy death.