It was desperately important for the believers of their belief system for some reason that others shared their beliefs because they assume that their religious doctrine is literally true, and then justify their beliefs because "God says so in their doctrine ".

 As one goes in deeper investigation find nothing satisfying in any religion.  The more he learns of any religious doctrine he become aware of the fact that, the religion is not the means for self-realization because the true ‘Self” is not the form but the true self is formless.  The religion is based on the false self [ego] and false experience (universe). Religion takes the false self as real self and false experience as reality. Thus whatever is based on the false self and false experience is bound to be falsehood.     

The obsession with "our sins" having been "washed away by water of river  would be regarded as evidence of a serious mental illness in an individual within any sane society, but when this is an obsession of millions of people it becomes "religious faith", held by many others to be something that should never be criticized.

It was desperately important for the believers of their belief system for some reason that others shared their beliefs because they assume that their religious doctrine is literally true, and then justify their beliefs because "God says so in their doctrine ".

 

Upanishads clearly declare:- 

Katha Upanishad 1:2:23 The Soul cannot be realized through hearing scholarly explanation of the discourses, not even by the intellect.

Katha Upanishad 1:3:6 “Through the knowledge of the Soul, God, one is pure and clean constantly.” Neither by reading the book, nor by taking a bath at holy place has one become pure. Inner purity is possible when one remains in constant touch with the Soul. Constant Soul-Consciousness is the real purity.

Kena Upanishad 2:4 When it is known through every state of cognition, it is rightly known, for (by such knowledge) one attains life eternal. Through one's own self one gains power and through wisdom one gains immortality.

Kena Upanishad 2:5

If here one knows it, then there is truth, and if here one knows it not, there is a great loss. Hence, seeing the Real in all beings, wise men become immortal on departing from this world.

Mundaka Upanishad 1:2:8

“Remaining in the fold of ignorance and thinking “we are extremely wise and learned,” the fools with boastful nature ramble about like the blind led by the blind alone.”

Mundaka Upanishad 3:2:3

 

“The weak and timid cannot realize the Self. Self-Realization is not possible through intellect or hearing spiritual discourse. One who welcomes God in every activity, through a thorough controlled and disciplined life, to him also the Soul is revealed."

Mundaka Upanishad 3:2:3

The Soul cannot be realized by the weak and timid.

It is no use of arguing with someone who has faith in his belief system because for him there can be no possible refutation of what he believes, so rational argument is entirely useless. He clings to his belief so strongly that he makes no distinction between the truth and his belief. One has to know the fact that god cannot exist without his existence. The truth does not depend on gods’ existence but it entirely depends on man’s existence.   Thus it is foolish to venture in knowing the truth of gods existence without verifying the facts about his true existence. 

Seeker has to have courage to accept the truth and reject the untruth. Most people will not be able to subscribe to path of truth because they sentimentally and emotionally involved with their inherited belief system and even if one does he has to overcome all his doubts confusion and despair.  These are problem for the seekers who are from religious back ground because of their conditioning and they are made to accept their blind belief as truth and their interest or insight is not deep. 

It becomes difficult for the orthodox cult to accept anything else as truth other than their accepted belief, which they hold as truth. Although all religious followers are participants alike in the spiritual endeavor of the world, overzealous   followers of each religion are not prepared to accord equal status to other faiths and assert the superiority of their own. Thus universal brother hood is total impossibility because it is difficult to accept anything other than their inherited belief system.        

Intense inner longing to know the ultimate truth will guide the seeker, he needs no other guide. People who think by worshiping their gurus as God in human form in order to get self-realization are unaware of the fact that, accepting someone as guru and himself as disciple is greatest obstacle in the path of truth. The person who accepts himself as guru is not a Gnani, because he has already accepted self as body whereas the self is not the body. The person who accepts himself as disciple of some guru also considers his self as body thus; it becomes a great hindrance in path of truth. Guru is essential in religious and yogic path but not for Self-Realization