Why there is no birth and death for the soul?

In 20th verse of chapter 2 of Bhagavad Gita for happiness, Lalwani explains that the soul cannot take birth either does it die. There is no past, present or future for the soul and is thus everlasting. He further cites examples of the sun which may be hidden by clouds but doesn’t disappear. Lalwani further explains that Krishna is the super-soul here, and Arjuna should listen to him.