If the self is not the body, then the birth, life, death and the universe are bound to be illusion.

If the self is not the body, then the birth, life, death and the universe are bound to be illusion.  If birth, life and death are illusion then all conducts actions and their fruits are mere illusion. If body is not the self, then the existence of god, heaven and hell is mere illusion.  If body is not the self then all religious beliefs of god is mere illusion.  If the body is not the self but the Atman (soul) which is in the form of consciousness is the true self, then there is no scope for second thing other than consciousness, therefore consciousness, which is Atman is Brahman or ultimate truth.  

The Brahman alone is real and eternal.  Thus whatever is real eternal has to be identified as god. To identify the real and eternal, one has to overcome the ignorance caused by the illusion. To overcome the ignorance one has to acquire the Self-Knowledge or Brahma Gnana or Atma Gnana. 

The individual experience within the dream is reality within the dream. Therefore waking reality is also is reality within the waking. This waking is parallel dream and dream is parallel waking. Only when self-wakes up in waking the dream becomes unreal. When the self-consciously wakes up in its formless nondual true nature in the midst of waking experience  then all the three states are  mere mirage created out of its formless nondual true nature.

The form time and space within the dream are falsehood when waking takes place. Similarly the form, time and space of the waking are also falsehood when wisdom dawns. The wisdom dawns only when one realize the self is neither the waking entity nor the dream entity. Thus it is erroneous to judge and reason and conclude the ultimate truth on the base of waking entity and waking world because waking experience itself is illusion

This universe is common to all of us, therefore one must include the universe his investigation in order to realize the ultimate truth or Brahman.   It is only after one has inquired into the nature of the objective universe, that he should inquire into who is the knower. If, however one   inquiries into the knower before the inquiry into the universe, then it is mere mysticism.  One must have the perfect understanding of what is what.

v  “What is the universe?

v  What is this ‘I’?

That is why Sri, Sankara indicated in (VC):- 63. Without causing the objective universe to vanish and without knowing the truth of the Self, how is one to achieve Liberation by the mere utterance of the word Brahman? — It would result merely in an effort of speech.

65. As a treasure hidden underground requires (for its extraction) competent instruction, excavation, the removal of stones and other such things lying above it and (finally) grasping, but never comes out by being (merely) called out by name, so the transparent Truth of the self, which is hidden by Maya and its effects, is to be attained through the instructions of a knower of Brahman, followed by reflection, meditation and so forth, but not through perverted arguments.

The universe exists because of consciousness. The moment the ignorance vanishes the universe with all its contents becomes unreal. Thus realizing the unreal nature of the universe or waking experience in the midst waking experience leads to self-awareness. Self-awareness frees one from experiencing the waking experience as reality.