Spirituality is not a religion. Spirituality is nothing to do with the religion and its concept of god and its code of conducts and its holy books. . Monotheism is based on the religion, not spirituality. The spirituality is based on the soul, which is present in the form of the spirit. And the religion accepts the experience of birth, life, death and world as reality, whereas Sage Sri, Sankara declares the world is unreal Brahman alone is real. Thus, the experience of birth, life, death happening within the unreal world is bound to be falsehood. Thus, the religious and religious belief and its ritual based on the birth entity, is bound to be falsehood. Thus, the seeker has to realize ‘what is that is real and eternal?
In Vedas the God has been described as: ~
Nirguna (Without form and properties).
All this the above is the nature of the soul, the innermost self. Thus the innermost self is God. That is Atman is Brahman. Brahman is God.
In Advaita Vedanta: - Brahman is without attributes and strictly impersonal. It can be best described as infinite Being, infinite Consciousness and infinite Bliss. It is pure knowledge itself, similar to a source of infinite radiance. Since the Advaitins regard Brahman to be the Ultimate Truth, so in comparison to Brahman, every other thing, including the material world, its distinctness, the individuality of the living creatures and even Ishvara (the Supreme Lord) itself are all untrue. Brahman is the effulgent cause of everything that exists and can possibly exist. Since it is beyond human comprehension, it is without any attributes, for assigning attributes to it would be distorting the true nature of Brahman. Advaitins believe in the existence of both Saguna Brahman and Nirguna Brahman; however they consider Nirguna Brahman to be the absolute supreme truth.
Atman is the innermost self. The Atman is present in the form of consciousness is ultimate truth or Brahman. Brahman is God.
Therefore, self-realization is necessary in order to realize the ultimate truth or God. Self-realization is real God realization. : ~ Santthosh Kumaar