Peter,
I'd also advise focusing on the content of the material, which in the letter Clement supposedly says was from Carpocrates himself and placed in Mark. This contrasts to the Stromata, where Carpocrates has left the scene, and the practices of the sect are said to be held by his son Epiphanes (not at all certain this is a biological son or metaphorical in the sense of Church succession, but it seems Clement thinks it's biological)" "This fellow Epiphanes,
whose writings I have at hand, was a son of Carpocrates and his mother was named Alexandria." At this point even if Epiphanes is a mere young leader of say his mid thirties or so (probably older since Clement has his writings in view) would make Carpocrates likely well deceased if not extremely aged in an era when fifty was an ancient. Yet in this letter he has knowledge of Carpocrates himself, unlike Stromata which is through his son.
Secret Mark's content, such as reported, is a pastiche from all the gospels. We have a parallel to Lazarus being raised in John, but now using the laying of hands (Mark 10:16 and //s), crossing to the "other side" of the Jordan (several synoptic "other side" + John 10:40 "across the Jordan"), and Jesus loving the disciple (John 13:23, 25, 19:26-27, 20:2, 21:7, 20, 24), Jesus rolling away the stone at the tomb is a nice enhancement of Jesus ordering Lazarus' stone be rolled. It is a curious twist that the young man is rich, as that is the opposite of the Lazarus and the Rich man story.
When you look at the material it's pretty clear the Secret Mark material came from a writer who knew John's gospel in Canonical form. This of course fits Clement's argument that it came from the Carpocrates. But does what is being described come anywhere close to the description of the sects rituals reported by Clement in the Stromata book 3? Not at all.
Clement's objection is the equality of women "These, so they say, and certain other enthusiasts for the same wickednesses, gather together for feasts (I would not call their meeting an Agape),
men and women together." (3.2.9) This he says after speaking of the points in their doctrine he holds as excellent. Essentially he is accusing the Carpocrateans of not respecting marriage because "woman can belong to all like animals", but it seems this is a slam at their agape meal for having Men and Women together. He makes the ridiculous charge that after this sacred meal "After they have sated their appetites, then they overturn the lamps and so extinguish the light that the shame of their adulterous "righteousness" is hidden, and they have intercourse where they will and with whom they will." I guess most of us Christians today are as guilty as the heretics Clement slams. Clement wants separate tables like Muslims have. Clement come back later and describes this meal as 'immoral communion.' (3.5.54)
Hum, where are those secret rituals? What I read from Clement and his saying that men and women eating the holy meal together will lead to wife sharing like animals, sounds like something coming from a crazed Salafist Imam about western women showing their hair in mixed company are whore who will sleep with anyone. The Imam is being blatantly propagandistic, and so is Clement.
What comes much closer to the secret Mark passage is his description in 3.4.27 of some unnamed sect where "they have impiously called by the name of communion any common sexual intercourse" to their interpretation of the kingdom of God. But this is not the Carpocrateans, it's some worse than the Nicolatians sect in his mind (again probably a gross exaggeration like out present day Salafist Imam).
We get another fantastic claim in the letter
"But since the foul demons are always devising destruction for the race of men, Carpocrates, instructed by them and using deceitful arts, so enslaved a certain presbyter of the church in Alexandria that he got from him a copy of the secret Gospel, which he both interpreted according to his blasphemous and carnal doctrine and, moreover, polluted, mixing with the spotless and holy words utterly shameless lies. From this mixture is withdrawn off the teaching of the Carpocratians."
This is very strange. Our letter Clement is saying that Carpocrates doesn't have a copy of Mark of his own, or that his sect had to go to extraordinary extreme measures to obtain one "to pollute." To say this doesn't sound plausible is an understatement. It implies that the sect had no access to regular Christian scripture. What other sect had this problem?
Additionally we get a comment unique to Clement about Peter being martyred in Rome and Mark going to Alexandria. Eusubius, an unreliable source to be sure, only reports that Clement says "Peter had preached the Word publicly at Rome," nothing of his martyrdom. This is a new element. It expands upon prior traditions we have from Clement. This is suspicious as well. Why mention it? What purpose would it have outside an encyclical letter? In short the letter seems all the more absurd, in that it follows the formula of pseudonymous letters of the church, encyclical, yet pretending to be for a single addressee.
There are just way too many suspicious elements and unanswered questions to accept Clement's letter as legitimate, and even more problems with the content called the Secret Mark. (Note nothing here has anything to do with Smith's take.)
You want to convince me, start with explaining the Pastiches.
“’That was excellently observed’, say I, when I read a passage in an author, where his opinion agrees with mine. When we differ, there I pronounce him to be mistaken.” - Jonathan Swift