I don't agree with that conclusion of the Naga Baba. If we agree that God is basically infinity (something all encompassing) then by definition it can have no opposite because it is all, i.e. there can't be a knower outside of it to know it. Thus it is impossible to know God, to comprehend infinity. However, because everything is contained within that infinity therefore the possibility may exist for a part of it to somehow become one with the infinity; technically a 'part' of infinity is never truly separate from it - all of the relative is contained within the absolute.
Non-duality is the only ontological explanation for reality that I have ever come across that is actually plausible and rings true. Every other explanation always resorts to installing boundary conditions or miracle events (Big Bang does both) in order to create sense. Downstream of non-duality the implications are that there is no space, no time, no motion, that everything relative is in relation to everything else relative because there is no real division, only some sort of self-refracting quality of the Absolute with respective to itself (infinity somehow dividing itself without breaking its contiguousness) that subsequently allows for all 'this' to appear as something separate from itself. The only 'thing' that could possibly meet the requirements for infinity, and infinity dividing itself infinitely, is awareness - how many times can you fold a piece of paper? I feel like I'm doing a disservice trying to put it into words, but;
I had an experience on NN-DMT, long before reading of the concept of non-duality, that matches perfectly with what it implies. I felt, directly, that the entire universe was emanating out from this infinitely large and infinitely small point right at the centre of 'me'. It was literally only a second or two, right after the visual aspect of the DMT trip ended but I wasn't back in regular eyes open consciousness yet, this sort of 'visually non-black indeterminate state' (I've felt something similar when exiting a dream but waking awareness hasn't started). It was the briefest of moments, but I felt like I knew who I really was, and that I was God.