"According to one version, which represented Dionysus as a son of Zeus and Demeter, his mother pieced together his mangled limbs and made him young again. In others it is simply said that shortly after his burial he rose from the dead and ascended up to heaven...
Turning from the myth to the ritual, we find that the Cretans celebrated a biennial festival at which the passion of Dionysus was represented in every detail...Where the resurrection formed part of the myth, it also was acted 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. A different form of the myth of the death and resurrection of Dionysus is that he descended into Hades to bring up his mother Semele from the dead."

[ Frazer, James.: The Golden Bough, Touchstone, 1963. Page 452 ]

As with Jesus, December 25th & Jan 6th are the traditional birth dates related to Dionysis, which simply denotes the time the Winter Solstice occurs, taking into account the variations caused by the 'precession of the equinoxes' over time.
Both of these days denote the Winter Solstice (or the birth of the Sun ), which is why the Armenian Church to this day still celebrates the birth of Christ on Jan 6th.
As Freke & Gandy reference St. Epiphanius on this point:

'St Epiphanius tells us that in Alexandria the birth of Osiris-Dionysus as Aion was celebrated on January 6...Those taking part then went by torchlight into an underground sanctuary from which they brought an image of the god carved in wood and marked with "the sign of a cross on hands knees, and head." The highlight of this mystery celebration was the announcement: "Today at this hour the virgin Kore has given birth to Aion (Dionysis)." '

[ Freke & Gandy: The Jesus Mysteries, Three Rivers Press p. 33 ]

Its interesting to point out that Communion as practiced today in the Christian world also had certain foundation with the cult of Dionysis, as Campbell points out:

"Dionysus-Bacchus...whose blood, in this chalice to be drunk, is the pagan prototype of the wine of the sacrifice of the Mass, which is transubstantiated by the words of consecration into the blood of the Son of the Virgin"

[ Campbell, Joseph: Creative Mythology, Penguin, p23. ]

"No explanation is needed to show how this very day came to be adopted for commemorating the marriage at Cana when Jesus performed the miracle which used to be performed by Dionysis..."

[Lietzmann, H: The History of the Early Church,Lutterworth Press 1961 ]

Dionysis, whose father, as in the Christiain story, was God but whose mother was a mortal woman [ semele], was represented in the East as a bearded young man of dignified appearence, who had not only taught mankind the use of the vine but... encourangeing peace. He like jesus, had sufferred a violent death, and had decended into hell, but his ressurection and ascension then followed...

[ Weigall, Arthur: The Paganism in our Christianity, Thames & Hudson, 1999 p220-224 ]

Other comparisons between Jesus and Dionysis:

Both are considered the " Savior of mankind".
Both are born of a mortal virgin.
Both( in certain versions ) are born on December 25th or January 6th ( the winter solstice ).
Both have a Birth Star.
Both are visited by Magi.
Both portrayed as a man with long hair and a beard.
Both turn water into wine.
Both perform other miracles.
Both are surrounded by disciples.

[ Freke & Gandy: The Jesus Mysteries, Three Rivers Press p. 60-61 ]