In oneness, longing for the other has been dropped, this is probably going to be the hardest part for you. Oneness happens when you find pleasure in being alone, it is no more loneliness because there is no more even a consideration about other - Jesus says to love your neighbor as yourself, it is because they are another expression of you. He has to say it in a dual way because otherwise it will not make sense...
The other does not exist, it is just like the thoughts going through your own head. Every decision you have ever arrived at, you have considered two or more alternative routes - the mind is not consistent, it has formed a panel to decide what to do, yet you define who you are by these conflicting views.
In oneness, none of this occurs, for there is no thought. There is only being, blissful happiness at the miracle of simply existing. Nothing else is needed, this is what is meant by "God sufficeth", nothing else but this is your longing. Buddha speaks of two kinds of people who fulfilling this longing: arhat and bodhisatva. Arhat is the male approach, he will probably retreat to the woods after enlightenment and be utterly alone until he dies. Bodhisatva is the female approach which is taught by Jesus and Krishna among others, this one will not retreat, he will return to the world and try to help others, he longs for all to enjoy this aloneness with him - a paradox, yet communal meditation is much more intense and powerful, more than this, he sees that nothing else compares.
The Bodhisatva has found the jewel of life and wants to share it, the arhat has found the jewel and has become lost in it. That jewel is oneness, but it is like the Bodhisatva sees his hand or foot is not as blissful as it can be, he wants all of his body to partake in that bliss. The arhat doesn't have a hand or foot, he is the bliss and nothing else. Both reside in oneness, though.
This is what is meant by realizing you are part of the body of Christ. I am as a Bodhisatva, I will not allow that this bliss be localized, I want it to be universal. This is looking more and more like a lost cause though, this forum is turning me into an arhat, for what is the point? If the foot wants to remain asleep, still the leg keeps me balanced, what does it matter?