In Celtic legends of Arthur and Gothic tales of Parsifal, warriors go in search of the Holy Grail. It is extremely unlikely that these stories postdate christianity. Instead, the grail came from much older shamanistic practices of ritual sacrifice, of which the clearest descriptions are actually from Astec and Maya histories, with some Greek examples too: a human victim's heart is cut open and his blood collected in a vessel as an offering to the gods.

It is necessary to realize that sacrificial victims were not always ill fated virgins,  slaves  and prisoners of war.  In both the Golden Bough and the White Goddess, it was pointed out that royalty was regularly sacrificed so that a younger person can succeed. This is also known in Tibetan history, with the early kings "returning to heaven" when their sons reach the age of 13 (or officially, old enough to ride horse), and hinted in Chinese myths, such as heaven sending a dragon to take Yellow Emperor up and Shang dynasty founder Tang offering to sacrifice himself during a great drought. It did greater honour to the gods to sacrifice a person of high status. In Zhou times it was still the practice to sacrifice a cow during royal summits, with each participant smearing blood on his lips as part of the oath swearing. One could therefore surmise that in the much earlier eras, the blood of the sacrificed king was collected in a vessel and used in the same way.

In some versions of the Grail story, it is indeed said that the vessel received the blood of Jesus; this however does not match the generally accepted description of the Gospels, as execution by crucification does not easily accommodate a knife stabbing and blood collection. Instead, the Catholic mass maintains the belief that wine in a vessel, symbolically or in some spiritual sense, is the blood of Christ, which is actually just the residue of old shaman ideas that have been absorbed into subsequent religions.

The version that the vessel was used by Jesus in the Last Supper also has its problems; first, why are the other utensils He might have used at the same meal less important than his cup? Second, since the grail is normally assumed to be made of gold, how could Jesus' group have this kind of luxury items for their meal?

The grail story is obscure because it was taken from the situation in which it fitted in naturally, and put into a situation where it does not have a well defined place, but in some ways this accounts for its fascination and provides scope for imagination.

圣杯的故事在英国凯尔特人的亚瑟王和古德意志人的帕希法传说中都有出现。这些故事是比基督教更古老的。也就是说，圣杯反映的是远古的巫术习俗。这在美洲的阿斯特和玛雅历史中讲述的最清楚，但在希腊历史中也有一些：祭司用尖刀割破人牲的心，把血收在杯中用以祭神。

人牲不一定只是处女，奴棣或战俘，欧洲古史中有很多杀旧王祭神让新王登基的故事，西藏也有“国王一到王子能乘马就回去天上”的记载，中国的故事比较模糊，但汤因旱灾以身为牲祷于桑林，黄帝乘龙归天， 鲧付以吴刀化为黄龙出禹，其实都是同类故事。用高级的人牲，是对天神特别敬重。周朝是有结盟仪式时，杀牛取血涂嘴唇；更古的杀老王祭天新王登基仪式中，可想象是用金杯收老王血再用于对新王效忠的盟誓仪式。

欧洲圣杯故事有些也是说用来收耶稣的血，但同他在十字架上受刑情况不合。天主教弥撒以酒代表耶稣的血，其实就是古老巫术的遗留。另有些说圣杯是耶稣最后晚餐用过的，但也有问题：为什么他用过的餐具中只有杯最重要？而且如果杯是金做的，耶稣一群人如何可能有这样的奢侈品？圣杯故事因为转移了时空，变得很模糊，但也因此留了很多想象空间。