On the other end of the spectrum are those who point out the New Testament insistence on unity and being of one mind and not having any divisions amongst us, such as 1 Corinthians 1:10ff:
I appeal to you, brothers, in the name of our Lord Jesus Christ, that all of you agree with one another so that there may be no divisions among you and that you may be perfectly united in mind and thought. My brothers, some from Chloe's household have informed me that there are quarrels among you. What I mean is this: One of you says, "I follow Paul"; another, "I follow Apollos"; another, "I follow Cephas"; still another, "I follow Christ." Is Christ divided? Was Paul crucified for you? Were you baptized into the name of Paul?It would seem safe to say that Paul would be appalled that today there are "Baptist Christians" and "Methodist Christians" and "Presbyterian Christians" and on and on.
It seems to me that the idea of "Unity in Diversity" is a cop-out; people claiming to follow Christ are too lazy to work out the differences so that unity would take precedence over diversity.
On the other hand, honest people sometimes have honest differences of understandings.
It is this "other hand" that Paul seems to tacitly recognize in his letter to the Galatians, when he recognizes the denomination of "Jewish Christians" and the denomination of "Gentile Christians", and particularly the "circumcision group" at Antioch (2:12).
These groups were divided on doctrinal issues no less than many of the doctrinal issues today.
Although Paul prefers that Christians be united, he admits that sometimes there are divisions, and these divisions do not in any way make one group less Christian than the other group.
Still, the aim should be for unity, not Unity in Diversity. Unity in Diversity is merely Plan B.