In the temporal world, we are two with "God". In my aimless wanderings on this planet, I am one only with myself. That is, most of the time I do not experience a connection with anything much more dramatic than my immediate surroundings. Not that the spirit is not there, somewhere, but generally I am looking at, for instance, trees, and thinking beautiful "trees," not beautiful "God." I am not connecting myself with my spirit in any active way.
A connection with my deeper self, God, the Great Spirit, the Universe, only happens when I specifically take the time to contemplate that connection. And to a great extent, it seems rather foolish to to be wondering where God is on my laptop, or in my TV or in the pot roast I am having for dinner. In many ways, God would just be an imposition to my everyday life
Not that it isn't there all the time, but a connection with whatever anyone wants to consider God is only as good as the experience we are having with it. That experience is available to us all the time, so in that sense we are one with our spirit. But all too often we are caught in our reasoning, our emotion or our body to give anything but short shrift to our spirit. It is then that we are two.
To fully experience our spirit we need to find a way (if only temporarily) to transcend our mind and body and engage fully with our spirit; to be aware of how we use or spirit. This requires the observation of our spirit as though it were not us, but a separate yet connected element of who we are. Not easy to do, but possible and powerful, particularly when it allows us to then realize that two are one. The same is true with our emotion, our reason and our body: our awareness of them gives us the ability to use each to our best advantage. Hey, perhaps it's not even duality, but more like quad-ality to which we should attend (reason, emotion, body, spirit).
So in the end I guess it's not about eliminating duality (quad-ality) as much as accepting that duality is built in to us. By learning to use duality as another tool for deepening our awareness, we become more clear about who we are, how we feel, what we know, and how our spiritual selves can be brought to bear in a greater world.