No one can prove the existence of god because whatever knowledge one has of GOD comes from the old scriptures which were written by great spiritual saints, who are no longer present to testify their writings.
The scriptures it self declare that: This Ataman 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 Ataman reveals Its own form. [Katha Upanishad Ch-II -23-P-20]
This Ataman cannot be attained through study of the Vedas, nor through intelligence, nor through much learning. He who chooses Ataman—by him alone is Ataman attained. It is Ataman that reveals to the seeker Its true nature. [ 3 –page-70 
Mundaka Upanishad Upanishads by Nikilanada]
Mundaka Upanishad Upanishads by Nikilanada]In Isa Upanishad says:
MANTRA 10
Scholars say that the path of Avidya [performing Aganihotra and other sacrifices] and the path of vidya [worshipping gods and goddesses] produce different results. Wise men confirm this. [X]
Vidya and Avidya both are hindrances to Self-knowledge, but Vidya is even worse than Avidya. The word Vidya is used here in a special sense; here it means worshipping gods and goddesses. By worshipping gods and goddesses you will go after death to the world of gods and goddesses. But will that help you? The time you spend there is wasted, because if you were not there you could have spent that time moving forward towards Self-knowledge, which is your goal. In the world of gods and goddesses you cannot do that, and thus you go deeper and deeper into darkness.
Avidya is Karama and therefore a hindrance. You perform Avidya - i.e., you perform Agnihotra and other sacrifices. This is a roundabout way of purifying the mind, and it is also groping in the dark. But it may not have as heavy a toll on your time and energy as the other.
If the self –knowledge is the goal, then it means belief in conceptual gods and worshiping the belief leads to deeper ignorance. Religion and its prescription of believing and worshiping gods are recommended for those who are not receptive and ready to receive the self-knowledge.
It proves that the concept of god, karma, heaven and hell are ideas created by religion, to help for those who are incapable of grasping. The concept of god and goddesses and karma are part of the ignorance. By worshiping god and goddesses one accepts the false self as true self, thus he is unfit for self-knowledge. Therefore concept of god is not the means to acquire the self knowledge. That is why Buddha rejected concept of God, religion and scriptures.
Therefore, it is necessary to make sure why the religion, concept of god and scriptures are not the means to self-realization before indulging in pursuit of truth.
