score:5
I think I found the source of this theory.
Google scholar has turned up this 1930 book: From Orpheus to Paul a History of Orphism. One recent publication that cites it is a 2008 thesis of Stian Sundell Torjussen from the University of TROMSΓ. I'll quote a passage from p.40 there:
Orphism was thus seen as taking a step beyond Greek religion, forming the vanguard of the Greeks evolutionary path towards monotheism. The first steps on this road were, as Macchioro argued, taken by the philosophers, especially Plato, who, deeply influenced by Orphic thought and doctrines, developed a system of thought which ultimately laid the foundations for Christianity.
However, Torjussen goes on to review work by later scholars, Willamowitz and Linforth in particular, who, according to him, demolished some of the more far-fetched claims of the Macchioro school (pp. 41-44).
It's actually quite fascinating reading, Torjussen does a very good job summarizing the debates.
I hope it answers your question!
P.S. Although I am not an expert by any means and can't even begin to evaluate at present the evidence of the allegedly Orphic tablets which seems to play a large role in this whole business. However, I'd like to throw in my own two cents: that early Christianity was influenced by Neoplatonism is well-known even to laymen like me, but I've always assumed that the influence comes from a stage a few centuries later (say, Origen). The attempt to backdate this to Paul is, in my eyes, a bit flimsy, because Paul was a Jew and could hardly be directly familiar with Greek rituals and mysteries before his conversion. So to posit that Paul was influenced by Orphism, one has to postulate some intermediate link, such as the Essenes - which lifts the whole thing to the rarefied realm of almost-unverifiable conjecture. But that's just my two cents, they could be total piffle, read Torjussen anyway!
Upvote:2
Check out this material
http://legacy.owensboro.kctcs.edu/crunyon/e261c/06-Plato/greek_mystery_cults.htm
The following has been taken from Will Durant, The Life of Greece, vol. 2 of The Story of Civilization, Simon and Schuster, 1966, 188-92.
If the verdict was guilty, there would be severe punishment. One form of the doctrine conceived this punishment as eternal, and transmitted to later theology the notion of hell. Another form adopted the idea of transmigration: the soul was reborn again and again into lives happier or bitterer than before according to the purity or impurity of its former existence; and this wheel of rebirth would turn until complete purity was achieved, and the soul was admitted to the Islands of the Blest. Another variant offered hope that the punishment in Hades might be ended through penances performed in advance by the individual, or, after his death, by his friends. In the way a doctrine of purgatory and indulgences arose. And thus there were in Orphism trends that culminated in the morals and monasticism of Christianity. The reckless looseness of the Olympians was replaced by a strict code of conduct; a conception of sin and conscience, a dualistic view of the body as evil and of the soul as divine, entered into Greek thought; subjugation of the flesh became a main purpose of religion, as a condition of release for the soul.
Here's a review on a book by another author Guthrie on similar material