Following the centuries during which the Roman Catholic Church, with its vast monastic properties and many churches, had become firmly established, the Reformation was slowly introduced. The city of Brunswick accepted Lutheranism in 1528, the duchy of Brunswick-Wolfenbüttel in 1568. The Enlightenment and rationalism, not pietism and revivalism, influenced this Christian community in the 18th and 19th centuries. After the abolition of the monarchy in Germany in 1918, the church was governed by the bishop. It went through many trials during the national socialist period.

There are also some free churches and several Orthodox congregations in the area. The church maintains good ecumenical relations with these churches and also with the Jewish community in its territory. It maintains special relations with Lutheran churches in Japan, India, Namibia, Czech Republic and, through the Evangelical Lutheran Mission in Lower Saxony, relations with several Lutheran churches in Africa and South America.