An interesting background on the origin of the belief in an immortal soul...it seems to have originated with Greek philosophy/paganism...the Israelite nation did not believe in the immortal soul...
The early Hebrews apparently had a concept of the soul but did not separate it from the body, although later Jewish writers developed the idea of the soul further. Biblical references to the soul are related to the concept of breath and establish no distinction between the ethereal soul and the corporeal body. Christian concepts of a body-soul dichotomy originated with the ancient Greeks and were introduced into Christian theology at an early date by St. Gregory of Nyssa and by St. Augustine.
Ancient Greek concepts of the soul varied considerably according to the particular era and philosophical school. The Epicureans considered the soul to be made up of atoms like the rest of the body. For the Platonists, the soul was an immaterial and incorporeal substance, akin to the gods yet part of the world of change and becoming. Aristotle’s conception of the soul was obscure, though he did state that it was a form inseparable from the body.
Soul | religion and philosophy | Britannica
The early Hebrews apparently had a concept of the soul but did not separate it from the body, although later Jewish writers developed the idea of the soul further. Biblical references to the soul are related to the concept of breath and establish no distinction between the ethereal soul and the corporeal body. Christian concepts of a body-soul dichotomy originated with the ancient Greeks and were introduced into Christian theology at an early date by St. Gregory of Nyssa and by St. Augustine.
Ancient Greek concepts of the soul varied considerably according to the particular era and philosophical school. The Epicureans considered the soul to be made up of atoms like the rest of the body. For the Platonists, the soul was an immaterial and incorporeal substance, akin to the gods yet part of the world of change and becoming. Aristotle’s conception of the soul was obscure, though he did state that it was a form inseparable from the body.
Soul | religion and philosophy | Britannica