Different Christian religious denominations had a formative influence on the 17th and 18th centuries. The monuments selected as examples allow us to this day to clearly track the different faiths.

In contrast to other regions, post-Reformation Westphalia had virtually no monasteries or convents abolished. Starting from the 17th century, some have even transformed into mixed denomination convents, where protestant and catholic nuns lived together.
One specific example of this is the convent founded around 1225 as a Cistercian convent Fröndenberg, in which, located in evangelical territory since the Reformation, Catholic, Reformed, and Evangelical nuns have been living. This rare tri-denominational situation arose as the result of an unclear political and legal situation following the death of the last Duke of Jülich-Kleve-Berg in the year 1609 between the Count von der Mark and Ferdinand, Archbishop and Prince-Elector of Cologne. The tolerance towards different faiths also shaped religious life in Fröndenberg outside the convent, where three parishes of different denominations shared one church.

In many places in the 16th-17th centuries, catholic churches were reused by protestant parishes. It was rare for one town to have two churches, as in Holzwickede-Opherdicke, where the parish had been lutheran since the late 16th century, but the nobility, having converted back to the old faith, established a Catholic church in 1683.
Building work on a new reformed church was initiated in April 1602 by the Electress Amalia von der Pfalz in Alpen am Niederrhein. There stands the oldest parish church in Germany as an architectural symbol of her faith.

Another influence was implemented in 1700 by two Catholic sisters, the Countesses von Nesselrode-Reichenstein. Educated in Cologne by the Ursulines, a female community founded in 1535 in Brescia Angela Merici, they were determined to use this ahead-of-its-time model as an example to create an institute for the education of young girls in the diocese of Münster.
Through their great involvement and support from their father, on November 3rd 1698, the foundation certificate was finally signed by Prince-Elector Joseph Clemens, and the convent and the school were built in Dorsten within the Vest Recklinghausen.

One of the few churches that remained catholic in the protestant Duchy of Mark even during the reformation is the Church of St Mary in Lünen.
As a Marian pilgrimage site, it ensured the survival of Altlünen after the displacement of the town to the southern bank of the Lippe between 1336 bis 1341, and also later, by drawing revenues from pilgrimage. It served as a parish church for catholics in Altlünen and those living south of the Lippe.

It was particularly in connection with pilgrimage that the parish clerk, organist and compiler of the first Catholic hymn book in German, Rudolph Nagell, rendered great service in the second half of the 17th century. In many ways, he is regarded as the source of impulse for the Re-Catholicization of the Lünen area. His cottage, built in 1690 in the domain of the prince-bishopric of Münster, still stands today in Lünen, where he was employed at the Church of St Mary in Altlünen, in the protestant County of Mark.