What was believed to show the first seed of the belief in an immortal soul?

The belief in an immortal soul is closely tied to the worship of Dionysius, who, in ancient Greek religion, was associated with rebirth, transformation, and the cycle of nature. Worship practices surrounding Dionysius celebrated themes of life, death, and regeneration, which contributed to the idea of an existence beyond physical life. His rituals often involved elements of ecstatic celebration and transcendence, promoting a concept of the soul that survives beyond earthly existence.

The other options, while significant in their respective mythologies, do not emphasize the idea of the soul's immortality in the same way that the worship of Dionysius does. Apollo is often associated with prophecy and healing, Hades with the afterlife but not with the concept of an immortal soul, and Zeus is seen primarily as a ruler of the gods rather than a deity directly tied to the notion of immortality or rebirth. The traditions and beliefs surrounding Dionysius provide a more direct connection to the early ideas of the soul's continuity after death.