I've never taken a close look the Mar Saba letter until now, and after reading it and this thread and poking around the internet, I don't see what the big deal is if Secret Mark is genuine. It seems to be more or less the same as the account of Lazarus in John. As Wikipedia puts it:One of the strongest arguments against its authenticity is the combination of the unlikelihoods that it would require:
(A) An alleged early Christian ritual practice - private gnostic-style instruction involving possibly disrobing and in my reading of the passage, homosexual activity - that was unknown or very rarely known until M. Smith's 20th c. discovery, was related in
(B) a gospel version (Secret Mark) that was unknown or very rarely known until the 20th c. discovery ...
In each story it is the sister whose brother just died who approaches Jesus on the road and asks his help; she shows Jesus the tomb, which is in Bethany; the stone is removed and Jesus raises the man from the dead, who then comes out of the tomb. In each story, the emphasis is upon the love between Jesus and this man, and eventually, Jesus follows him to his home. Each story occurs “at the same period in Jesus’ career,” as he has left Galilee and gone into Judea and then to Transjordan.
https://en.wikipedia.org/wiki/Secret_Gospel_of_Mark
I couldn't say if what Clement (or whoever is purporting to be him) says about the origin of Secret Mark is correct (that Mark had added things to his earlier work), but if Carpocrates had obtained a copy of it, then why couldn't John, or whoever added it to John (like the passage about the adulterous woman, which John or an interpolator could have known from Papias or an oral tradition)?
I also don't get the impression that there is anything homosexual about Secret Mark; no more than the story of Lazarus at least, and Clement cites Secret Mark preceisely to counter the idea that it contained anything homosexual:Bishop J.B. Lightfoot wrote that absence of the passage from the earliest manuscripts, combined with the occurrence of stylistic characteristics atypical of John, together implied that the passage was an interpolation. Nevertheless, he considered the story to be authentic history. As a result, based on Eusebius' mention that the writings of Papias contained a story "about a woman falsely accused before the Lord of many sins" (H.E. 3.39), he argued that this section originally was part of Papias' Interpretations of the Sayings of the Lord, and included it in his collection of Papias' fragments. Bart D. Ehrman concurs in Misquoting Jesus, adding that the passage contains many words and phrases otherwise alien to John's writing.
However, Michael W. Holmes has pointed out that it is not certain "that Papias knew the story in precisely this form, inasmuch as it now appears that at least two independent stories about Jesus and a sinful woman circulated among Christians in the first two centuries of the church, so that the traditional form found in many New Testament manuscripts may well represent a conflation of two independent shorter, earlier versions of the incident." Kyle R. Hughes has argued that one of these earlier versions is in fact very similar in style, form, and content to the Lukan special material (the so-called "L" source), suggesting that the core of this tradition is in fact rooted in very early Christian (though not Johannine) memory.
https://en.wikipedia.org/wiki/Jesus_and ... Authorship
After these words follows the text, "And James and John come to him," and all that section. But "naked man with naked man," and the other things about which you wrote, are not found.