This is more about how literal concrete operational faith can be.
The Quest of the Holy Grail (thirteenth century CE Britain, written in Norman French) tells the story of the knights of the Round Table, followers of King Arthur in Britain, who go out on a quest to find the Holy Grail after seeing a vision of it in Camelot. This is a spiritual quest rather than a literal adventure. Everything that happens to them is an allegory. Most of the knights fail to have very many adventures, mostly because they are not spiritual enough to find them. Some of the more famous knights do have adventures, but fail to achieve their goal because of their sinfulness. Only the purest of the knights, Galahad, Perceval and Bors, can succeed. Lancelot comes close, but his sinfulness in having had a twenty-four year affair with Guinevere the wife of King Arthur has tainted him beyond redemption, so even the most sincere repentance only allows him a partial vision of the Grail.
Purity, in this tale, is taken literally. Galahad and Perceval are virgin in both mind and body, having never felt or acted on lustful thoughts, and so are spotless and deserving of success in the quest. Bors is slightly tainted, as he had sex once but has since remained chaste. He also will be successful, though he will return to Camelot at the end of the quest rather than die in the last resting place of the Grail as the others do. Perceval’s aunt (a holy woman) explains this to him early in the quest.
‘Sweet nephew, it so happens that you have kept so close a watch upon yourself till now that your virginity was never once abused nor smirched, nor have you ever known in verity the nature of the flesh or carnal union. And this was most essential for your good; for had your body been violated by the corruption of sin, you would have forfeited your primacy among the companions of the Quest, even as Lancelot of the Lake, who through the lusts and fevers of the flesh let slip long since the prospect of attaining what all the rest now strive after. Therefore I implore you to keep your body as undefiled as the day Our Lord made you a knight, so that you may come pure and unsullied before the Holy Grail, and without stain of lechery. Where is the knight can boast so fair an exploit? There is not a man of all your fellowship that has not sinned in this respect, save only you and Galahad, the Good Knight I have told you of.’ [The Quest of the Holy Grail, chapter 6; Matarasso translation:102]
The devil tries to tempt both Bors and Perceval into having sex, but they are able to protect themselves from temptation and complete the quest. Galahad is so pure that the enemy doesn’t even bother to tempt him. He is so pure that he can perform miracles. In this he is a latter-day Jesus. When he meets the four-hundred-year-old blind King Mordrain, who has been awaiting him so he can die, the king regains his sight and health and says:
‘Galahad, servant of God, true knight whose coming I have so long awaited, take me in your arms and let me lie on your breast so that I may die in your embrace, for you are as pure and virginal compared to other knights as the lily flower, the symbol of virginity, is white beyond all other. You are the lily of purity, you are the true rose, the flower of strength and healing with the tint of fire: for the fire of the Holy Ghost burns in you so brightly that my flesh which was withered and dead is now made young and strong again.’ [The Quest of the Holy Grail, chapter 15; Matarasso translation:269]
Gawain, one of the impure knights, has a dream about 150 bulls in a field, all but three of which are spotted. He has this interpreted by a holy man:
‘Among the bulls were three that were unspotted, or in other words were without sin. Two were white and fair, and the third bore traces of spots. The two that were white and fair signify Galahad and Perceval, who are whiter and fairer than any other knight. They are truly fair, being perfect in every virtue, and their whiteness is so immaculate and pure that one could scarcely find today the smallest spot upon them. The third, that bore traces of spots, is Bors, who once abused his virginity, but has since atoned so fully by his purity of life that the offence is wholly pardoned. The three bulls were yoked together at the neck, which is to say that virginity is so engrafted in these knights that they are powerless to lift their heads: meaning they are secure against the assaults of pride.’ [The Quest of the Holy Grail, chapter 8; Matarasso translation:170]
Gawain himself is so full of sin that he has no hope at all of attaining the quest and might as well go home.
Lancelot, on the other hand, has a vision of the Grail but is helpless to respond because of his sinfulness. A holy man advises him that he too impure to complete the quest, but if he repents and does penance he may be permitted another vision of the grail:
‘Thus endowed with every good quality a mortal man could have, you entered the high ranks of chivalry. But when the enemy, who first brought man to sin and led him to damnation, saw you so armed and girt on every side, he feared that he would never catch you out. . . . He gave much thought to the best way of ensnaring you and making you commit a mortal sin, and concluded at the last that the shortest cut to success lay through a woman. . . .
‘With that he entered into Queen Guinevere, who had not made a good confession since she was first married, and roused her to cast frequent looks at you as you tarried in her apartments on the day you were knighted. Growing conscious of her glances, you turned your thoughts to her; and at once the enemy let fly a dart which caught you undefended and knocked you off your balance with such force that you stumbled from the path of righteousness and set your feet in one unknown to you till then, the path of lust, the path which degrades both body and soul to a degree that none can really know who has not tried it. From that time on the enemy robbed you of your sight. . . .
‘Thus you were lost to Our Lord, who had nurtured and enhanced you and equipped you with every virtue, and had called you even to the honour of His service.’ [The Quest of the Holy Grail, chapter 7; Matarasso translation:142-143]
He does have another vision, after much questing, then goes home and resumes his affair with Guinevere.
Virginity was also prized by Buddhist monks for spiritual reasons. In The Journey to the West (China, 1592), Tripitaka Tang is kidnapped by a female demon who is desperate to seduce him and thereby attain the power of his pure yang energy (yang is masculine, yin is feminine, and having never been with a woman he is uncontaminated by yin energy). I suppose this would be a nice change from being kidnapped by demons who want to eat his pure flesh in order to gain a thousand years of immortality, which seems to happen to him a lot, but even so Tripitaka is not interested, much to the annoyance of one of his spirit guides, who would be happy to take his place. Tripitaka is forced to hold out until his spirit guides can rescue him, which they do.
Virginity in these tales is more magical than practical. Of course virginity can also have practical benefits. It can be a way of keeping your energy from getting too scattered, when you want to concentrate on one thing in particular, rather than lead a more conventional balanced life. It’s not the emphasis on virginity per se that makes this philosophy concrete, but the rationale behind it.