A man who starves body for the good of soul

One word substitute is Ascetic.

Monk: a member of a religious community of men typically living under vows of poverty, chastity, and obedience.
Ascetic: characterized by severe self-discipline and abstention from all forms of indulgence, typically for religious reasons.
Saint: a person acknowledged as holy or virtuous and regarded in Christian faith as being in heaven after death.
Spiritualist: a person who believes that the spirits of the dead can communicate with living people.