The one soul becomes many, says the Gita. So also Guru Nanak.
If the souls merge back, the one soul remains.
The many are there because there is the one.
Also souls are self-existent and unborn.
Souls do not die, say both the Gita and Guru Nanak.
The Quran says souls die.
By soul the Quran means body.
That leaves us only one option.
We must verify the eternal soul.