"Consequently, if we were to say that we enjoyed fellowship with him and still went on living in darkness, we should be both telling and living a lie. But if we really are living in the same light in which he eternally exists, then we have true fellowship with each other, and the blood which his son Jesus shed for us keeps us clean from all sin. If we refuse to admit that we are sinners, then we live in a world of illusion and truth becomes a stranger to us." (I John 1:6-8 Phillips)
What is true fellowship with one another? It is God's truth at the center of our existence. Truth puts aside all walls that we put up. When we decide the other person is "not good enough" or "does not measure up" or whatever reason we give for denying fellowship with that person we are not living the truth. We sin so much. Christianity abounds with hindered fellowship and the only reason can be sin. And the only one we have control over is ourselves. Truth shedding light on our own sins, eliminates our lofty,"I am not as bad a sinner as you", illusory lens of condemnation or criticism of others. Christ did NOT say, "you have to achieve this behavior or this status or this characteristic before I love you." Yet we withhold love from our fellow believers and family members if they do not live up to what we want them to be. Christ loved us first and before we loved Him and extends love to us while we are yet sinners. True fellowship is when we are more and more like Him, when we admit our sin, when we come out of darkness, and not just at salvation or conversion, but every day of life here.