I thought of myself as a Buddhist for a while, and I have some commentary on your question. You ask what Buddha meant when he said that we are all one being. First, I would contend that there is no simple answer to that question, and second, It bears mentioning that The Buddha spent his whole life breaking down the barriers that kept him from realizing that everything is one. You can't hope to make the same realization in moments. But here's the great ontological paradox of Buddhism; a Buddhist who is not enlightened believes that all things are one, in fact they probably know beyond a shadow of a doubt that all things are one, but they probably haven't realized that all things are one. So, is it real yet? I mean, if you haven't realized it, is it simply imaginary? Further, all things as one; imagine a giant radio station somewhere in space sending out signals which instruct atoms on how to behave. Hence, creating a sort of a system of individual parts within one unified whole. Only, that radio station isn't divine. It's just the collective of all the atoms. Or something like that. I find this stuff really hard to visualize.