Up to the affiliation with France, Rhenish Hesse consisted of 28 differently governed territories. The Peace of Augsburg established the principle "cuius regio eius religio" (whose region, his religion), which allowed the princes of states to dictate the confession. Frequent changes of the princes also changed the main confessions a lot. Therefore there were often three confessions (Protestant, Lutheran and Roman Catholic) in one place with corresponding churches, schools, pastors and teachers. During the period of affiliation with France, many things were reorganized but the coexistence of the confessions remained the same. Many Protestant theologians and parishes considered this to be antiquated. After the victory over France 1814, when Rhenish Hesse was governed by an administration of Bavaria and Austria, the Protestant structures collapsed and there were only Protestant communities without guidance. The victors established quickly a collective leadership for reformists and Lutherans in Worms. This process of reorganization and classification into state structures was continued by the Grand Duchy of Darmstadt, to which Rhenish Hesse belonged after the Vienna Congress from 1816 onwards.
Three principles promoted the desire for a new collective order and a joint service for all Protestants:
You can find more information: 500 years of Reformation in Rhenish Hesse, article “Rhenish Hesse and the church union of the two Protestant confessions” (original German: „Rheinhessen und die Kirchenunion der beiden protestantischen Konfessionen“) by Tobias Kraft.