First is the Beaver-Butler initiative to recognize the existence of irreconcilable differences. Denominations are not included in Scripture, nor in the early church, nor in the Reformation. They are largely an American invention, which has been regrettably translated to mission cultures, but which are not a part of either the gospel or our saving faith. Denominations as great programmatic entities are strictly a late 19th and early 20th century phenomena. Looking at the present effectiveness of mission efforts around the world, they may well have passed the time of their usefulness.
Denominations have their reality in the reality of human taste.
Some folks like order, others like enthusiasm. Some like authority, others like town meetings. Some like tight structure, others like loose structure. There is no reason everybody has to have one or the other. God, in the holy wisdom of sacred history, has permitted us to express our Christian faith in a multitude of different cultures, structures, forms, entities.