I’m still looking at J. G. Frazer’s list of sources. The next one is this:
Where the resurrection formed part of the myth, it also was enacted at the rites,  and it even appears that a general doctrine of resurrection, or at least of immortality, was inculcated on the worshippers; for Plutarch, writing to console his wife on the death of their infant daughter, comforts her with the thought of the immortality of the soul as taught by tradition and revealed in the mysteries of Dionysus.
 Plutarch, Consol. ad uxor. 10. Cp. id. Isis et Osiris, 35; id., De ei Delphico, 9; id., De esu carnium, i. 7.
So, let’s look these up. First Plutarch, Consolatio ad uxorem. Bill Thayer again comes to our rescue with an online version here. Bolding and paragraphing is mine.
10. Furthermore, I know that you are kept from believing the statements of that other set, who win many to their way of thinking when they say that nothing is in any way evil or painful to “what has undergone dissolution,” by the teaching of our fathers and by the mystic formulas of Dionysiac rites, the knowledge of which we who are participants share with each other.
Consider then that the soul, which is imperishable, is affected like a captive bird: if it has long been reared in the body and has become tamed to this life by many activities and long familiarity, it alights again and re-enters the body, and does not leave off or cease from becoming entangled in the passions and fortunes of this world through repeated births.
For do not fancy that old age is vilified and ill spoken of because of the wrinkles, the grey hairs, and the debility of the body; no, its most grievous fault is to render the soul stale in its memories of the other world and make it cling tenaciously to this one, and to warp and cramp it, since it retains in this strong attachment the shape imposed upon it by the body.
Whereas the soul that tarries after its capture but a brief space in the body before it is set free by higher powers proceeds to its natural state as though released from a bent position with flexibility and resilience unimpaired. For just as a fire flares up again and quickly recovers, if a person who has extinguished it immediately lights it again, but is harder to rekindle if it remains extinguished for some time, so too those souls fare best whose lot it is, according to the poet,
“Soon as they may pass through Hades’ gates”
before much love of the business of our life here has been engendered in them, and before they have been adapted to the body by becoming softened and fused with it as by reagents.
Is it me, or is this about reincarnation or the transmigration of souls, rather than “resurrection”?
Next, Isis and Osiris 35:
35. That Osiris is identical with Dionysus who could more fittingly know than yourself, Clea? For you are at the head of the inspired maidens of Delphi, and have been consecrated by your father and mother in the holy rites of Osiris. If, however, for the benefit of others it is needful to adduce proofs of this identity, let us leave undisturbed what may not be told, but the public ceremonies which the priests perform in the burial of the Apis, when they convey his body on an improvised bier, do not in any way come short of a Bacchic procession; for they fasten skins of fawns about themselves, and carry Bacchic wands and indulge in shoutings and movements exactly as do those who are under the spell of the Dionysiac ecstasies. For the same reason many of the Greeks make statues of Dionysus in the form of a bull; and the women of Elis invoke him, praying that the god may come with the hoof of a bull; and the epithet applied to Dionysus among the Argives is “Son of the Bull.” They call him up out of the water by the sound of trumpets, at the same time casting into the depths a lamb as an offering to the Keeper of the Gate. The trumpets they conceal in Bacchic wands, as Socrates has stated in his treatise on The Holy Ones. Furthermore, the tales regarding the Titans and the rites celebrated by night agree with the accounts of the dismemberment of Osiris and his revivification and regenesis.
Similar agreement is found too in the tales about their sepulchres. The Egyptians, as has already been stated, point out tombs of Osiris in many places, and the people of Delphi believe that the remains of Dionysus rest with them close beside the oracle; and the Holy Ones offer a secret sacrifice in the shrine of Apollo whenever the devotees of Dionysus wake the God of the Mystic Basket. To show that the Greeks regard Dionysus as the lord and master not only of wine, but of the nature of every sort of moisture, it is enough that Pindar be our witness, when he says
May gladsome Dionysus swell the fruit upon the trees,
The hallowed splendour of harvest time.
For this reason all who reverence Osiris are prohibited from destroying a cultivated tree or blocking up a spring of water.
Again, how does this justify the claim made?
Next, De ei Delphico, 9 (On the word ‘ei’ engraved over the gate of the temple of Apollo at Delphi, from the Moralia). This I was unable initially to locate online, but is in fact here.
IX. “If, then, anyone should ask, What has this to do with Apollo? We reply: It has to do not only with him, but with Bacchus, who has no less property in Delphi than Apollo himself.
We therefore hear theologians, partly in verse, partly in prose, setting forth and chanting how that the god, though by nature incorruptible and eternal, yet, as they tell, through some decree of fate, submitted to changes of condition, at one time set all Nature on fire, making all things like to all; at another time he was metamorphosed and turned into various shapes, states, and powers, in the same way as the universe now exists—but is called by the best-known of all his names.
The wiser sort, cloaking their meaning from the vulgar, call the change into Fire ‘Apollo,’ on account of the reduction to one state, and also ‘Phoebus’ on account of its freedom from defilement and purity: but the condition and change of his turning and subdivision into airs and water and earth, and the production of animals and plants, they enigmatically term ‘Exile’ and ‘Dismemberment.’ They name him ‘Dionysos’ and ‘Zagreus’ and ‘Nycteleos’ and ‘Isodi’; they also tell of certain destructions and disappearances and diseases and new births, which are riddles and fables pertaining to the aforesaid transformations: and they sing the dithyrambic song, filled with sufferings, and allusions to some change of state that brought with it wandering about and dispersion.
For Aeschylus says: ‘It is fitting the dithyrambus, with its confused roar, should accompany Dionysos: but Apollo, the orderly and sober paean.’ The latter god they represent in pictures and images as exempt from age and youthful; but the other, under many guises and forms; and, generally, to the one they assign invariableness, order, and unmixed seriousness; whilst ascribing to the other a mingled playfulness and mischief, gravity and madness, they proclaim him ‘Evius inciter of women, flourishing with frenzied honors, Dionysos!’—not wrongly taking what is the characteristic of either change.
For, since the duration of the periods of such changes is not equal, but that of the one which they call ‘Satiety’ is the longer of the two, and that of the oracle giving the shorter, they observe the due proportion here, and during the rest of the year they employ the paean at the sacrifices; at the beginning of winter they revive the dithyramb and put a stop to the paean, and invoke the god with the former instead of the latter chant for the space of three months: which makes three to one the space of time they believe that the creation lasted compared to that of the conflagration.”
Um. Not much here either.
Next, De esu carnium i.9 (On eating meat — it seems to be i.7 in fact). After rejecting eating the bodies of animals he goes on.
Yet perhaps it is not unsuitable to set the pitch and announce the theme by quoting some verses of Empedocles. . . . By these lines he means, though he does not say so directly, that human souls are imprisoned in mortal bodies as a punishment for murder, the eating of animal flesh, and cannibalism. This doctrine, however, seems to be even older, for the stories told about the sufferings and dismemberment of Dionysus and the outrageous assaults of the Titans upon him, and their punishment and blasting by thunderbolt after they had tasted his blood — all this is a myth which in its inner meaning has to do with rebirth. For to that faculty in us which is unreasonable and disordered and violent, and does not come from the gods, but from evil spirits, the ancients gave the name Titans, that is to say, those that are punished and subjected to correction. . . .
This seems again to be about reincarnation. There might even be an implication of reincarnation into the bodies of animals in this.
So … do these passages back up the comments of Frazer? It seems unlikely.
The terms “resurrection” and “immortality”, loaded with Christian significance as they are, give an impression somewhat at odds with the comments of Plutarch. Reincarnation, yes, into the bodies of animals and men, yes — resurrection, no. Immortality of the soul, yes — of the body, no. We need not consider this portion of Frazer’s claims, useful though it is to see these passages.