Chemistry ceases to improve when one element is found from which all others are deductible. Physics ceases to progress when one force is found of which all others are manifestations. So religion ceases to progress when unity is reached, which is the case with Hinduism.
The Soul is not composed of any materials. It is unity indivisible. Therefore it must be indestructible.
There is only one Soul in the Universe. There is no 'you' or 'me'; all variety is merged into the absolute unity, the one infinite existence - God.
Jiva (individual soul) is the conscious ruler of this body, in whom the five life principles come into unity, and yet that very Jiva is the Atman, because all is Atman.