To truly believe and embrace this way of being everyone must be included. We don't get to pick and choose who we will be 'at one' with. If we do, then we're not truly walking the path of Oneness.
It's so easy to be 'at one' with those who share our belief systems and those with whom we've chosen to interact with in this particular dance of life. It's much more difficult to be 'at one' with those we have judged to be less than we would have them be.
For me, this has been a bit of a challenge. It's not difficult to feel a sense of unity and Oneness with certain individuals I interact with. Much more difficult, however, with others.
But I'm working on it. Some days I will do better than others. Some days I will fail miserably. I'll use the feelings of the better days as a goal of where I'd like to be. I'll use the miserable days as a reminder of where I don't want to revisit.
And when I can look at each being I interact with and feel that I am them and they are me I know I will be walking in Oneness.