Many people see the existence of denominations as a blot against the church's witness to unity.
To understand this counterintuitive historical reality, one has to look back 400 years to the century following the Protestant Reformation. Nonconformity could not be tolerated, and the truth was worth fighting for. And fight they did. This truce allowed Calvinism to join Lutheranism and Catholicism as a recognized expression of the Christian faith. In contrast to the majority who held to Presbyterian principles and expressed these convictions in the Westminster Confession of Faith, the Independents followed congregational principles.