The only satisfactory discussions on the subject, for me, have come out of Plato. Robert Schmidt does an amazing job of articulating this.
Plato maintained that you can't have this "oneness" or "separateness" without each other. He called them the same and other (as well as limit and limitless, one and many, etc). You can't have same without some kind of identity that establishes as a distinguishing factor, yet you can't have otherness without some kind of commonality, either with onesself or with the principle that establishes identity. Ultimately it's impossible to resolve this issue into one - the two have to exist side by side. If you have same, you have the possibility for something "other than". If you have other, the opposing sides still have to partake of a certain uniformity in order to establish a difference.
At one point the mind and world were considered distinct, but not intrinsically separate. The world was that which emitted an effluence and the mind received it. They were dinstinct, and differently defined, but not separate. The sameness and otherness exist within the same space (as in quantum mechanics, to my understanding).
Empowering yourself for the good of the whole can both be for yourself (the same) and the whole (others). All at the same time.
Good comment. The point is to experience the oneness - and there is a definite experience of that state. Without that basic experience, it is just ideas and words. After the experience, two things happen: firstly, we return to our standard duality with a new perspective; and we also have the opportunity to integrate that inner core with our daily life.
Think of it a base or root consciousness - I'm not a fan of quantum mechanical analogies, but here it comes! It is somewhat like the ground state, where apparently nothing exists yet is the source of existence.
Yes, we are all connected, but that does not mean one amorphous hive-mind blob of consciousness; it means we have the same ground state. hence, it may be possible, one day, that we may all agree on reality!