Final answer:
Dionysos (Bacchus) is called the 'twice-born' god due to his unique birth narrative, where he was born from Semele and then reborn from Zeus's thigh, and the significance of rebirth within the Bacchic Mysteries and Orphic traditions.
Step-by-step explanation:
Dionysos (Bacchus) is called the 'twice-born' god because of the mythological circumstances of his birth, which are unique among the Olympian deities. According to the myth, Dionysos was first born from the goddess Semele and then reborn from Zeus's thigh after Semele's death, making him the only Olympian to have a mortal mother and to be born twice. The mythological narrative explains the dual nature of Dionysos, embodying both the aspect of mortality through his human mother and immortality through his father Zeus.
The concept of rebirth is also deeply ingrained in the Bacchic Mysteries and the Orphic traditions. Initiation rituals often involved the symbolical death and rebirth of the initiate, representing a spiritual transformation akin to Dionysos's own rebirth. The belief was that followers of Dionysos could experience a form of mystical rebirth, with the potential for happiness in the afterlife, through participation in these rites.