The
attested Marcionite text is much simpler, which I show here from my reproduction, with footnotes
15:1 Γνωρίζω δὲ ὑμῖν, ἀδελφοί, τὸ εὐαγγέλιον ὃ εὐηγγελισάμην ὑμῖν, (1) ὃ καὶ παρελάβετε, ἐν ᾧ καὶ ἑστήκατε,
Now I make known to you, brothers, the Gospel which I preached to you, which you received, in which you also have stood,
15:2 δι᾽ οὖ καὶ σῴζεσθε, τίνι λόγῳ εὐηγγελισάμην ὑμῖν εἰ κατέχετε, ἐκτὸς εἰ μὴ εἰκῇ ἐπιστεύσατε.
if you hold fast the word which I preached to you, unless in vain you believed.
15:3 παρέδωκα γὰρ ὑμῖν ἐν πρώτοις, (2) ὅτι Χριστὸς ἀπέθανεν ὑπὲρ τῶν ἁμαρτιῶν ἡμῶν
For I handed on to you, in the very first things, that Christ died for our sins,
15:4 καὶ ὅτι ἐτάφη, καὶ ὅτι ἐγήγερται τῇ ἡμέρᾳ τῇ τρίτῃ, (3)
and that he was buried, and that he was raised on the third day,
15:11 εἴτε οὗν ἐγὼ εἴτε ἐκεῖνοι, οὕτως κηρύσσομεν καὶ οὕτως ἐπιστεύσατε. (4)
Therefore whether I or they, so we preach and so you believe.
Footnotes:
(1) Epiphanius P42 "on the raising of the dead" γνωρίζω δὲ ὑμῖν, ἀδελφοί, τὸ εὐαγγέλιον ὃ εὐηγγελισάμην ὑμῖν
(2) Western non-interpolation (Latin b, Ambrosiaster, Irenaeus latin, Tertullian) "that which I also recieved" ὃ καὶ παρέλαβον was almost certainly not in Marcion, as it implies a teacher-student relationship, clearly rejected by Marcion (see Galations 1:11-12, 15-17a)
(3) M 3.8.5; Tradidi enim, inquit, vobis inprimis, quod Christus mortuus sit pro peccatis nostris, et quod sepultus sit, et quod resurrexerit tertia die. 'For I delivered, he says, to you first of all, that Christ died for our sins, and that he was buried, and that He rose again the third day'; DA 5.6 Epiphanius P42 ὅτι Χριστὸς ἀπέθανε καὶ ἐτάφη καὶ ἐγήγερται τῇ τρίτῃ ἡμέρᾳ and ~ τῇ τρίτῃ ἡμέρᾳ support F G K L P Ψ 049 maj, but not reflected in Tertullian; both accounts delete – κατὰ τὰς γραφάς (probably also delete verse 5ff)
(4) AM 1.20.4 sicut et alibi, Sive ego, inquit, sive illi, sic praedicamus. AM 4.4.5 Sive ego, inquit Paulus, sive illi, sic praedicamus; Epiphanius P42 οὕτως κηρύσσομεν καὶ οὕτως ἐπιστεύσατε
None of the witness accounts is attested in Marcion's version. This is hardly surprising. But the differences are greater than that. Here is a brief list
15:3 ὃ καὶ παρέλαβον "that I also received"
This is a reference to Paul receiving the tradition of Christ rising, e.g., the Jerusalem council. This contradicts the statement in earlier part of the verse παρέδωκα γὰρ ὑμῖν ἐν πρώτοις "which I handed down to you FIRST." This serves to make Paul's message less singular, part of a larger tradition. This is very different from the Marcionite Paul who is introduced in the Marcionite letters with Galatians 1:1 and 1:12 where he receives no tradition from men or any man but from direct revelation from Jesus Christ.
15:3 and 15:4 κατὰ τὰς γραφάς "according to the scriptures"
This is a reference to the claim of Christ fulfilling the OT prophecies, an anathema to Marcion's Paul. Again it is an authority other than Paul's revelation. This is the same adjustment in the Catholic introduction of Paul in Romans 1:2.
Then comes the appearances. I think the key think is the order
1) to Cephas (Peter)
2) to the five hundred (not part of the eleven/twelve apostles)
3) to James
4) to the Apostles
5) to Paul
These are in effect a ranking. And it is a ranking of teachings. We know that Peter is considered the orthodox here, Paul the Marcionite and Gnostic. So their being first and last respectively has relevance and should not be surprising. James is generally associated with Ebionite type sects. The Apostles is a bit more varied, but we could assume its the traditions of Catholic letters (Jude, John, etc) and various Acts (Thomas, Judas, Philip, et al.) of various schools. The five hundred is more of a mystery, so I'm happy to just see what other think and know of this myth which is the basis of the thread.
In fact verses 15:8-10 are chalk full of antidotes to the Marcionite presentation of Paul, to reduce his stature and minimize his authority.
In 15:3 Paul says he first (ἐν πρώτοις) handed down the tradition of Christ raised - that is he was the first one to do so. But in 15:8 he is "last of all" (ἔσχατον δὲ πάντων) to know the tradition, to have seen Christ risen. Paul's authority from Galatians 1:15-16 is said to have been exalted and set apart from other men even before birth (ὁ ἀφορίσας με ἐκ κοιλίας μητρός μου) to have Christ revealed (ἀποκαλύψαι) in him. But in 1 Corinthians 15:8 Paul's birth is denigrated, compared to a shameful abortion (ὡσπερεὶ τῷ ἐκτρώματι). These are not compatible. Finally Paul humbles himself, almost prostrate in verse 15:9, not as the first (πρώτοις) but as the least of the Apostles (ὁ ἐλάχιστος τῶν ἀποστόλων). This is as far from the Marcionite Paul as one can get. A refernce is made to the Saul persecution story from Acts as reason for this lowly status. And as a final coup de grace to his authority, in verse 15:10 he says his teachings are not so much from him as because of the grace of God, as if he were a mere vessel for it to pass through.
The focus of the material found in our received version is clear when contrasted with the Marcionite version. It is a reflection of the internal sectarian conflicts of the second century church, with the author attempting to reduce the stature of Paul's teaching within the overall church presentation. The traditions of the appearances are legends, not so much historical as representative of rank and order of the schools the heroes in each account represent. Carrier ignores this and so his conclusion in this case is weak, since it ignores the context of the material.
The writer of the traditions may well have no clue to the relative veracity of any of the appearance accounts. That is not his aim. He wants to establish rank of schools each tradition represents, his own the highest, the Gnostic/Marcionite the lowest.