This is a subject of some interest. I address similarities here: How do Dionysus and Jesus Relate?
SUMMARY: There are undeniable parallels between Dionysus and the Christ, but these are mainly physical, and there are important divergences. The moral dimension of self-sacrifice in the Greek and Roman canon evolves over time, from Homer (Iliad) to Ovid (Hercules), and finds its fullest expression, per sacrifice for all humanity, in Plato (the Crito).
In terms of sacrificing himself for humanity, as in the case of the Christ, I don't really see that element in the Greek canon with Dionysus, except in the idea that wine is a boon for mankind--warms you when cold, consoles you in sorrow, gives you courage when afraid, etc.
But when a man has reached the age of forty, he may join in the convivial gatherings and invoke Dionysus, above all other gods, inviting his presence at the rite (which is also the recreation) of the elders, which he bestowed on mankind as a medicine potent against the crabbedness of old age, that thereby we men may renew our youth, and that, through forgetfulness of care, the temper of our souls.
SOURCE: Plato "Laws", Book 2
But the gift of Dionysus is also double edged:
And is not this exactly the opposite of the potion described just now? For, first, it makes the person who drinks it more jovial than he was before, and the more he imbibes it, the more he becomes filled with high hopes and a sense of power, till finally, puffed up with conceit, he abounds in every kind of licence of speech and action and every kind of audacity, without a scruple as to what he says or what he does. Everyone, I imagine, would agree that this is so.
SOURCE: Plato "Laws", Book 1
So Zagreus (Dionysus) is violently torn apart by Titans, but it is involuntary. It's related to pity, but that element is most emphasized in the Bacchae of Euripides, in the person of Pentheus (literally "divine agony") who dies in the most horrific way imaginable so that Thebes may eventually be redeemed.
The sparagmos (death by dismemberment) is followed by omophagia, the eating of the blood flesh, in both the story of Zagreus and the Bacchae. (See East Coker [B])
Important to note that Dionysus in the Bacchae is depicted as having horns. This is contrary to portrayals of Jesus, but does show up in Michelangelo's very famous sculpture of Moses. Fauns, associated with Dionysus through Silenus, likewise have horns.
My understanding is that Christian ethics arise partly out of Ancient Greek humanist ideas (starting with Socrates[A]), and from Hebrew scripture with the idea that "love of the other" is the central tenet [see Hillel "the rest is just commentary" and Leviticus 19:18.)
The Christ takes it to the next level, in actually sacrificing himself for all humans.
In the Ancient Greek canon, We do see several demigods (one divine parent, one mortal parent) in the Greek canon with parallels:
- Dionysus as dying/resurrected, sacrament of wine = "resurrection in spirit"
- Heracles self-immolation related to pity (pietà), leads to immortality
- Achilles self-sacrifice, based on glory, but for the benefit of the Achaeans
Heracles and Dionysus are literally "sons of god" because "Dios" (Διός) is the most common epithet for Zeus, not "Ζεύς".
Achilles' father is a mortal Peleus, married to the goddess Themis because of a prophecy that "her son would be greater than his father." Zeus made this marriage to avoid being overthrown, but in some sense he failed, in that the Iliad, as a subversive text, diminishes the dignity of the Olympians and elevates the dignity of man--worship of the Olympians has faded, but the Iliad is still celebrated.
Hector, in particular, is shown in the noblest light, and his body is incorruptible after death:
Aphrodite, goddess of love, kept dogs from him by day and night alike, and with oil anointed him, rose-sweet, ambrosial, to the end that Achilles might not tear him as he dragged him. And over him Phoebus Apollo, son of god, drew a dark cloud from heaven to the plain, and covered all the place whereon the dead man lay, lest ere the time the might of the sun should shrivel his flesh round about on his sinews and limbs.
SOURCE: Homer, Iliad, Book 23
Redfield writes that Hector is "a martyr to loyalties, a witness to the things of this world, a hero ready to die for the precious imperfections of ordinary life." [The Tragedy of Hector]
Returning to Plato, it is ultimately Socrates who selflessly sacrifices himself for all mankind.
I strongly recommend taking a look at his Apology, which isn't an apology at all, but a calling out of the corruption of the power structure of the time. (Sound familiar? :)
Even more important is the Crito, where Socrates, most wise, makes the point that injustice answered by injustice is not a remedy.
Thus, "turn the other cheek", even if it means dying for what is right. For Socrates, like Jesus, setting an example was more important than his own life.
Unlike Dionysus, whose sacrifice is involuntary, Socrates' is voluntary. So while there are physical parallels between Dionysus and Jesus, the moral dimension of self-sacrifice in Greek mythology arises out of the Iliad, with Hector in particular, and finds its fullest expression in Socrates.
[A] "Socrates ... is neither the founder of the theory of ideas nor a legendary figure but rather a practical moral teacher mainly concerned with the cultivation of man, his self-development, and self-unfolding into full humanity. Socrates asking questions on man's nature and trying to answer them without an appeal to transcendent forms is what Versenyi believes most authentically Socratic and what he has chosen to call Socratic humanism. As the author himself recognizes there is nothing revolutionary about this view."
SOURCE: Socratic Humanism (review)
[B] From East Coker, Four Quartets:
"The dripping blood our only drink,
The bloody flesh our only food:
In spite of which we like to think
That we are sound, substantial flesh and blood—
Again, in spite of that, we call this Friday good."
Here, Eliot draws a parallel between Dionysus and the sacraments of Wine and Bread. The bread is literally the body of god. [See also: John Barleycorn]