The first point to observe when speaking of Christian Unity is that God is always working for unity; it follows, therefore, that if we are working against unity we are opposing God’s purposes, no matter how admirable our aims may seem to be.
Secondly, however, diversity is difficult; there has never been a time when unity was easy in the Church. Acts of the Apostles can make for discouraging reading for contemporary Christians with its claims that, ‘all the believers were on the same case, and held everything in common’ (2:44), and that, ‘the whole group of believers were of one heart and mind’ (4:32); but even the author of that slightly idealised picture is well aware that it was not always like this. There is, for example, the disedifying tale of Ananias and Sapphira (5:1-11), which is never read out in church, even though it follows immediately after this last passage. Or there is an alarming account of racial and religious discrimination in the seemingly harmonious community at Acts 6:1-6; that episode actually led to the appointment of the seven deacons, all with impeccably Greek names, to wait at table (though as a matter of fact, the only two about whom we ever hear again are Stephen and Philip, who are not serving up food, but preaching the gospel). So we must expect Church unity to be a tricky thing to handle.