To understand the unique location of this church, i.e. in the attic of a merchant’s house, and its clandestine use over the centuries, it is necessary to dive into the history of the Dutch Republic.
In the 16th Century, the Low Countries were ruled by the Catholic Spanish Habsburg royalty. At that time, Protestants, primarily Calvinists, constituted a significant minority. In a society dependent on trade, freedom and tolerance were considered essential. Nevertheless, Charles V (1500–1558), and later Philip II (1527-1598), felt it was their duty to fight Protestantism, which they considered heresy. The harsh measures led to increasing grievances in the Low Countries and in the second half of the century, the situation escalated. Iconoclastic mobs went on a rampage in August 1566, smashing the treasures of many churches. This is seen as the start of the Revolt of the Netherlands (1566–1648).
Philip II instructed the duke of Alba, a veteran of many campaigns, to march north and to restore order. Spain was initially successful in suppressing the rebellion. In 1572, however, the rebels conquered Brielle, and the rebellion resurged. The Spanish sent an army to attempt to reestablish their rule. Over the following years, the new Spanish governor Alexander Farnese (Duke of Parma) reconquered the major part of Flanders and Brabant, as well as large parts of the northeastern provinces. The Roman Catholic religion was restored in much of this area. On January 6, 1579, the Southern States (today mostly in France and part of Wallonia) signed the Union of Arras (Atrecht, now in northern France), expressing their loyalty to the Spanish king.
On 26 July 1581, seven United Provinces (Holland, Zeeland, Utrecht, Gelderland, Overijssel, Friesland and Groningen) declared their independence from the Spanish king.
The northern provinces grew to become a world power through its merchant shipping (the Dutch East India Company (Vereenigde Oostindische Compagnie (VOC), was established in 1602) and experienced a period of economic, scientific, and cultural growth. The Southern Netherlands remained under Spanish rule.
In 1648, the Republic of the United Provinces was officially recognized in the Peace of Westphalia also known as the Treaties of Münster and Osnabrück.
In the Dutch Republic, the ruling class was made up of an aristocracy of city-merchants. The main religion was Calvinism, which emphasized Christian virtues of modesty, cleanliness, frugality, and hard work. The declaration of 20 December 1581 officially prohibited the overt practice of the Catholic religion. However, while Calvinism became the dominant faith, many Catholics remained faithful. At first they had to clandestinely practice their faith. Therefore private churches were not unusual in the Northern Netherlands in the 17th Century. They celebrated mass in their living rooms, places of work and warehouses, frequently with the tacit consent of the authorities, who were often prepared to turn a blind eye for a small favor, as long as the churches remained unrecognizable from the outside.
The church in the attic on the Oudezijds Voorburgwal and Heintje Hoekssteeg was one of several such house churches in Amsterdam in the second half of 17th Century. In 1795 all religions were given the freedom to build their own places of worship openly, but for a variety of reasons new Catholic churches were not built until about the 1860s.
The church, which served a Catholic community over the centuries, had various names:
The most important was ‘Het Hart’ (after Jan Hartman, the wealthy merchant who built the church) ; ‘Het Haantje’ (the cockerel, referring to Heintje (Haantje) Hoekssteeg); from 1854-1888 ‘Parochie-kerk van den H. Nicolas binnen de veste’ (Parish Church of St. Nicholas within the walls); ‘Ons Lieve Heer op Solder ‘ (Our Lord in the Attic, a 19th Century name).
The hidden church in the attic was in use from 1663 onwards and hosted baptisms, weddings and masses. This continued until 1887, when its much larger successor, St. Nicolas church on Prins Hendrikkade, was dedicated. The attic church ceased to function as a church and in 1888 a group of Amsterdam Catholics who had formed 'De Amstelkring' foundation bought the building to safe it from demolition. Museum Amstelkring, was opened to the public on 28 April 1888. In 1951 monthly mass was reinstated by a group of artists from Amsterdam.
The church actively participates in the celebration of Sinterklaas, a traditional Dutch festival celebrated on December 5th each year. The origin of this popular festival is the fact that St. Nicholas is the patron saint of this church. St. Nicholas was the bishop of Myra (modern-day Turkey) and died on 6 December 340. St. Nicholas bones were moved from Myra to Bari in Italy, a region that used to be part of the large Spanish empire for many years, which may be the origin of this belief.
His death is observed in most Roman Catholic countries primarily as a feast for small children. In the Netherlands however, the eve of his feast day (December 5th) is celebrated nationwide by young and old, Christian and non-Christian as ‘Sinterklaas’, a corruption of ‘Sint Nicholas’. It is a festival for exchanging gifts and making good-natured fun of each other.
The folkloristic celebration of Sinterklaas is based on the story that Sinterklaas lives in Spain where he keeps records of children’s’ behavior. He is assisted by ‘Zwarte Piet’ (Black Peter). In November, Sinterklaas travels with his white horse and Zwarte Piet by steamship from Spain to the Netherlands. There are many traditional songs and rhymes that children still sing today to welcome him. On the night of December 5th, he rides across the rooftops and rewards the good children with presents. Zwarte Piet jumps down chimneys and makes sure that the carrot or hay the children have left for the horse in their shoes by the fireplace is exchanged for a small gift or some candy.
It is also custom for Sinterklaas to visit schools and public places (in this case the church) where he will call each child up to him to ‘discuss’ his or her behavior, after which the child will receive a small gift.