Sri a-TB sir,
I was a physicist once, so let me explain the way I always think. First, what is Brahman? There are two fold explanations, the existence of such an entity and so, then what is the nature of such an entity.
The existence of Brahman is very obvious. If one accepts science, the validity of ‘big bang’ theory, for it to have happened, creating both space and time, there must have been a cause. To me that cause is called Brahman. Even if one does not accept the ‘big bang’, one still needs to explain the existence of the physical universe we see and again, one needs to explain the cause.
So, then what is the nature of such an entity? Here, we can not use science to understand the nature. Because we are the ones that observe with our five senses to collect data, are ourselves part of the system. There is a well known theory that says that one can not understand what is outside an enclosed system, being part of the system. So, we can not perceive the nature of creator with our outwardly turned mind and senses.
But, then, as luck would have it, if we turn our focus inwards, through our mind, it is found that, we can indeed ‘know’ that creator. This is the concept of Advaitha.
But other ‘faiths’ say that there is a God as separate entity outside our universe who is all powerful, most excellent etc. But to ‘know’ that entity one has to wait till the end of time, when based on merits and demerits, one gets either eternal happiness or eternal suffering.
So, for my make up Advaitha makes sense. Not only because I am mentally constituted to like it, but because my genes come from a line of my ancestors who were all Advaithins and we all know how such ancestral thinking and behavior affect as to who we are today.
Secondly, Advaitha claims that one need not wait till the end of time to be in an eternal happy state, you can do it here and now. How? By understanding who we really are, that is permanent, that is universal and timeless. This is Brahman. Now, without going in to details about Maya, Atma, Ishwara, Karma, Dharma etc., to accept this lofty claim, one just needs to look for evidence, whether there is anyone who is believable who claimed to have achieved such a state of bliss. To one’s astonishment, one finds that such people are there, throughout history, to the present time in all cultures.
So, if one believes this, one has to take ‘instructions’ from one of those. For me again, because of my make up, it is Ramana Maharishi. Others follow others. I have faith that my guru achieved such a state and so whatever teachings that come out of such a person will not lead me astray.
This is all I can say. I do not know about the validity or the non validity of any other path. But since I started this mental journey more than a decade ago, I can attest to the fact that I am more and more at peace within myself.
This is a very long post. But I thought we can have a starting point, while answering some of your questions. Thanks.