Causality taught in the Upanishads is only to enable us to understand the supreme truth of no-origination. The world is not different from the Soul, the innermost Self. The Soul, the innermost Self is present in the form of the consciousness. The Soul is ultimate truth or Brahman or God.
The consciousness is not different from the world, in which we exist. The world is only an illusion created out of the consciousness. The consciousness appears as the diverse world If it really became diverse then the immortal would become mortal.
The dualists who seek to prove the origination of the unborn, by that very enterprise try to make the immortal, mortal. Ultimate nature can never change - the immortal can never become mortal and vice versa.
Sage Sri, Goudpada quotes from the Upanishads: ~ “There's no plurality here"; "The Soul through its powers appears to be many"; "those who are attached to the creation or production or origination go to utter darkness"; "the unborn is never reborn, for what can produce it?".
Katha Upanishad:~ This Atman cannot be attained by the study of the Vedas, or by intelligence, or by much hearing of sacred books. It is attained by him alone whom It chooses. To such a one Atman reveals Its own form. (Katha Upanishad Ch-II -23-P-20)
Mundaka Upanishad: ~ This Atman cannot be attained through the study of the Vedas, nor through intelligence, nor through much learning. He who chooses Atman—by him alone is Atman attained. It is Atman that reveals to the seeker Its true nature. (3 –page-70 Upanishads by Nikilanada)
The above passages further prove that: Self-knowledge cannot be attained by the study of the Vedas and intellectual understanding or by bookish knowledge. Therefore, the Vedas and other scriptures are not the means to acquire the non-dual wisdom. That is why Buddha rejected the scriptures, and even Sri, Sankara indicated that the truth lies beyond religion, the concept of god and scriptures.
When Upanishads declare that: ~ This Atman cannot be attained by the study of the Vedas, or by intelligence, or by much hearing of sacred books, then why to compare Vedas with Bible or Koran or any other religious scriptures to realize the ultimate truth, which is beyond form, time and space.
The religion was introduced in the past for the benefit of the populace who are incapable to grasp the ultimate truth. Thus, religion is nothing to do with the
pursuit of the truth because the truth is not belief and religion is based on the belief.
In theology, everyone is entitled to his own view, i.e. what he likes, but in pursuit of truth this is not permissible. That which dupes most of the people are taking satisfaction for truth. The seeker has to be aware of that which satisfies his feelings. "Felt" experience is no guide to the highest because one’s feeling may differ from others.
The Truth must be independent of one’s Self; it is not to be what pleases him: all prejudices must go. Those who talk of "I feel so and so" provide psychological and not spiritualistic reasons. Devotees seek to know God because they seek some benefit; seeker of truth seeks to know him in truth. The Steadiness of mind depends upon what one is interested in. One’s mind can be steady only on what his mind is attached to.
Things and problems concerning truth appear simple at first, and hence ordinary people speak presumptuously and glibly about it. But when one inquires he finds how little he know and that they are extraordinarily complex and he is obliged to go deeper and deeper into them.
One readily takes it for granted that both he and others knows what objects are or what the universe is because he has such immense conceit. Such an easy attitude arises because he does not know the complexity of these apparently simple matters, which in turn arises because of lack of inquiry and reasoning on the true base.
A person with emotion who changes from one path or school of thought to another, he looks for novelties that appear charming to him.