If the man had seen God creating the world, he could admit it, but how could he have seen God before he came into existence? +

Yajurveda – chapter- 32:~ God is  Supreme Spirit has no ‘Pratima’ (idol) or material shape. God cannot be seen directly by anyone. God pervades all beings and all directions.

God with form, name, and attributes does not find any support from the Vedas.

Sage Sankara’s Supreme Brahman is impersonal, Nirguna (without Gunas or attributes), Nirakara (formless), Nirvisesha (without special characteristics), immutable, eternal, and Akarta (non-agent). It is above all needs and desires. It is always the Witnessing Subject. It can never become an object as it is beyond the reach of the senses. Brahman is non-dual, one without a second. It has no other besides it. It is destitute of difference, either external or internal. Brahman cannot be described because the description implies a distinction. Brahman cannot be distinguished from any other than It. In Brahman, there is not a distinction between substance and attribute. Sat-Chit-Ananda constituted the very essence or Svarupa of Brahman, and not just Its attributes. The Nirguna Brahman of Sage  Sankara is impersonal.

Even  Bhagavad Gita says: ~ Brahmano hi pratisthaham ~ Brahman (God) is considered the all-pervading consciousness, which is the basis of all the animate and inanimate entities and material. (14.27).

When Bhagavad Gita says, God is considered the all-pervading consciousness which is the basis of all the animate and inanimate entities and material then nothing has to be accepted as God other than consciousness.

Even Brihadaranyaka Upanishad: ~ Brahman (God in truth) it is the form of the Athma, and it is indeed Athma itself.

Even Rig Veda: ~ The Atman is the cause; Atman is the support of all that exists in this universe. May ye never turn away from the Atman, the Self. May ye never accept another God in place of the Atman nor worship other than the Atman?" (10:48, 5)

Brihadaranyaka Upanishad says:~ "He who worships the deities as entities entirely separate from the Self does not know the truth. For the Gods, he is like a pasu (beast)". (1. 4. 10) 

Remember:~ 

If God is the formless Spirit, then how does man know God created the world? There is no proof. If man had seen God creating the world, he could admit it, but how could he have seen God before he came into existence? (i.e. were created).

The Spirit is the root element of the universe. The Spirit is present in the form of the Soul, the innermost Self. The Soul is present in the form of consciousness. 

From the Spirit, the universe comes into existence. In the Spirit, the universe resides. And into the Spirit, the universe is dissolved. The Spirit is the parent of all that is there.

No one has seen God creating the world. No one can claim that he was the first Knower of creation. How can anyone know God created the creation when he himself is part of the creation?

People talk about God creating the creation as if they were present when God was creating the creation. So people who wrote creation and creator theory existed prior to God creating the creation. 

There got to be at the very beginning of the creation, someone or another who was the very first knower of the creation. There cannot be something ‘known’ in the absence of a ‘knower.’

In Brahma Sutras Sage Sankara takes for granted, and assumes that a world was created: He there mixes dogmatic theology with philosophy.

That God created the world is an absolute lie; nevertheless, you will find Sage Sri, Sankara (in his commentary on Vedanta Sutras) clearly says this! He has to adapt his teachings to his audience, reserving the highest for philosophical minds.

The text of Brahma Sutras is based on religion and dogmatism, but in the commentary, Sage Sri, Sankara cleverly introduced some philosophy.

A number of Upanishads are equally dogmatic and self-contradictory because they also begin by assuming Brahman. Few Upanishads prove Brahman at the end of a train of proof but still, they are very confusing and vague.

The causality and creation but are for religious people only. Religion is only for those who are unable to understand the truth beyond form, time, and space. Religion is not final. It only gives satisfaction to the populace. The Self - knowledge is for the whole of humanity to free them from experiencing birth, life, death, and the world as reality.

Sage Sankara himself had often said that his philosophy was based on Sruti, or revealed scripture. This may be because Sage  Sankara addressed the ordinary man, who finds security in the idea of causality and thus, in the idea of God—and Revelation is indispensable to prove the latter. He believed that those of superior intelligence, have no need for this idea of divine causality, and can, therefore, dispense with Sruti and arrive at the truth of Advaita by pure reason.

People of small intelligence follow religion and believe that God created the world. However, how do they know that He did so? When a pot is created, one can see both pot and its maker, but not in the case of the world.

The seeker has to begin his analysis with the world first, not with the Soul, which is present in the form of consciousness. In the world in which you exist, consciousness is the finality. Thus, consciousness is the ultimate truth, Brahman, or God in truth. 

The universe is merely an illusion created out of God. In reality, the illusion and God are one in essence. Thus, consciousness, God is one without the second. Those who are stuck with the creator-creation theory will not be able to realize God in truth.

A Gnani sees the world in which he exists as the consciousness." However, to know this, they must study and be examined. : ~Santthosh Kumaar