'We frequently approach Christian unity as something that follows from what we are or what we do: we see Christian unity as constituted by doctrinal agreement or by moral alignment. We consider there to be no meaningful between someone who takes a different position on this or that doctrinal issue or this or that moral position. The way we approach evangelical ethics often reflects this. Even if we have a good emphasis on unity, it is often understood as an imperative modeled on Jesus' willingness to love the other, which still needs a move toward agreement by dialogue. But proper reflection on the sacraments confounds this: for Paul, our unity is a function of our union with Christ, which is a union with the one God, whose oneness becomes ours. Our attempts to draw a circle around those who think like us is fundamentally wrongheaded and, frankly, sinful. Now, this is not to say that it is wrong to pursue moral and theological agreement in the truth; it is important to do so, but we do it to bring the highest glory to God, not to define who is in and who is out. I am united to the believer whose doctrine is dreadful and to those whose life I find abhorrent; it is precisely because they share in Christ's body that I am compelled to speak to both problems, but to do so in brotherly love and affirmation. For Paul, the sine qua non of inclusion seems to be limited to the confession "Jesus is Lord," which can be made only by the acting presence of the Holy Spirit (1 Cor.12:3).'
Grant Macaskill, Living in Union with Christ, p.70.
