A certain perception of unity often leaves people critical of Christianity. The varieties of Christian denominations dwarf Basking Robins 31 flavors. In fact, just the varietals of Baptists leave people spinning as to why so many. Most people consider this an expression of the divisive nature of people. To be sure there is some truth to that. Just consider the wrangling in 1 Corinthians.
But, sometimes it is the result of finite expressions of an Infinite Triune God. Jesus prayed for unity among those who would follow him then and today (John 17). Certainly that did not necessarily mean uniformity. Read the differences between the players in Acts 16. One a slave girl and one a Philippian jailer. One used for the financial gain of others and one used in the oppression of others. Though both encountered the Liberating King. Both at the point of “What will I do?”
What we do will be born out in the end. Sometimes we do not like looking with the end in view. Especially if we have created a neat way to avoid responsibility. Not so fast reminds the Revelation (22). What will you do?
I agree that denominations can be a finite expression of an infinite God. But what do we do when we fall back on our doctrines to justify unbiblical, or extra biblical beliefs? Some of these beliefs have become so pernicious in the church that they are downright sinful.
I agree that unity is hard to accomplish in the church, but that does not mean that we do not strive to be more unified with our fellow believers in everything we do.