Why is reincarnation central to Spiritist belief?

In Spiritist belief, reincarnation is central because it serves as the mechanism for the soul's ongoing evolution. Spiritism posits that humans are essentially spirits temporarily inhabiting physical bodies. The purpose of these repeated incarnations into the physical world is to facilitate a journey toward intellectual and moral perfection.12

After the death of the physical body, the soul resides in the spirit world—often for a duration comparable to its previous life—before being reincarnated to continue its development. This process is viewed as a long-term journey that extends far beyond a single life and death. Allan Kardec, the founder of Spiritism, interpreted passages from both the Old Testament and New Testament as evidence for this cycle of rebirth. By undergoing these successive lives, spirits are able to progress and learn, which is a foundational tenet of the doctrine's philosophy regarding the nature and destiny of spirits.132