The Netherlands underwent one of the fastest and most complete secularizations in modern European history. In 1960, approximately 80 percent of the Dutch population identified with a Christian denomination. By 2020, this figure had reversed: the Central Bureau of Statistics reported that 54.1 percent of the population claimed no religious affiliation, marking the first time non-religious citizens formed an absolute majority. This transformation, often called "ontkerkelijking" in Dutch, was not gradual erosion but acceleration, particularly between 1970 and 2000 when church membership declined by roughly 2 to 3 percentage points per year. The speed distinguishes the Netherlands from neighboring countries like Belgium or Germany, where secularization proceeded more incrementally. By 2023, surveys consistently showed non-religious identification between 55 and 60 percent, depending on methodology and question framing.
Among those who retain religious affiliation, Roman Catholicism remains the largest single denomination, though concentrated regionally rather than distributed nationally. The 2019 census data indicated approximately 20.1 percent of the population identified as Catholic, down from 40.5 percent in 1971. The geographic distribution reflects historical patterns: Catholicism dominates in the provinces of North Brabant and Limburg in the south, where the Catholic share exceeds 50 percent in some municipalities. In contrast, provinces above the major rivers—particularly in the historic Reformed heartland—show Catholic populations below 10 percent. The Netherlands contains one archdiocese, Utrecht, and six suffragan dioceses: Haarlem-Amsterdam, Rotterdam, Breda, 's-Hertogenbosch, Roermond, and Groningen-Leeuwarden. Weekly Mass attendance has declined more steeply than nominal affiliation: studies from the Catholic University of Nijmegen in 2018 estimated that only 2.3 percent of self-identified Catholics attend services weekly, down from approximately 47 percent in 1970.
Protestant Christianity in the Netherlands exists in multiple organizational streams, reflecting historical divisions that remain meaningful despite declining overall membership. The Protestant Church in the Netherlands, formed in 2004 through merger of the Dutch Reformed Church, the Reformed Churches in the Netherlands, and the Evangelical Lutheran Church, constitutes the largest Protestant body with approximately 1.8 million members in 2022, representing about 10 percent of the population. This merger was itself a response to declining numbers and the practical difficulties of maintaining separate administrative structures. The more conservative Reformed Churches in the Netherlands (Liberated), which separated in 1944 over theological disputes regarding common grace, maintains approximately 270,000 members concentrated in the "Bible Belt," a region stretching from Zeeland through the Betuwe area to Overijssel and parts of Drenthe. In these communities, particularly in municipalities like Urk, Staphorst, and several towns in Veenendaal and Nunspeet, church attendance remains above 60 percent and daily life retains visible religious structuring.
The historical division between Catholic south and Protestant north shaped Dutch political and social organization until the late 20th century through a system called "verzuiling" or pillarization. This arrangement, which functioned most completely between approximately 1917 and 1960, organized Dutch society into vertical pillars based on religious and ideological identity. Catholics, Protestants, Socialists, and Liberals each maintained separate schools, hospitals, trade unions, newspapers, radio and television broadcasters, sports clubs, and political parties. A Catholic child might attend Catholic schools, join Catholic youth organizations, read Catholic newspapers, listen to the Catholic radio broadcaster KRO, support Catholic football clubs, and eventually vote for the Catholic People's Party without substantive interaction with Protestant or Socialist institutions. This system allowed minorities, particularly Catholics who had faced discrimination in the Protestant-dominated state, to build parallel institutions and political representation. The Netherlands had Catholic and Protestant universities: the Catholic University of Nijmegen (now Radboud University, founded 1923) and the Free University of Amsterdam (Vrije Universiteit, founded 1880 on Reformed principles). Pillarization dissolved rapidly after 1960 as secularization removed the religious basis for institutional separation, though remnants persist in the school system where approximately 60 percent of primary schools retain formal religious affiliations, even as actual religious instruction and practice within these schools has diminished substantially.
Sunday observance patterns illustrate the practical manifestation of secularization in daily rhythms. In 1960, most retail commerce ceased on Sundays throughout the Netherlands due to both legal restrictions and social consensus rooted in Christian practice. The Sunday Closing Act of 1953 prohibited most commercial activity, with enforcement strongest in Reformed Protestant regions. This changed through incremental legislative relaxation: municipalities gained authority to grant exemptions in 1976, and the 1996 Shop Opening Hours Act transferred primary authority to local governments. By 2023, Sunday shopping had become standard in major cities and tourist areas. Amsterdam, Rotterdam, Utrecht, and The Hague permit unrestricted Sunday commerce. Smaller municipalities vary: in the Bible Belt, many shops remain closed on Sundays by merchant consensus rather than legal requirement. Urk, a former island fishing community of approximately 21,000 people with Orthodox Reformed majority, maintains near-complete Sunday closure. Businesses that open on Sundays in these communities sometimes face social pressure or lose customers. The reverse pattern appears in secular areas: in Amsterdam, Sunday has become indistinguishable from other days in commercial terms, with major shopping streets along Kalverstraat and in the Jordaan district maintaining full weekend operations.
Islam has become the second-largest religious community in the Netherlands, though measurement varies significantly depending on methodology. Statistics Netherlands reported in 2021 that approximately 5 percent of the population identified as Muslim, representing about 850,000 people. Different surveys produce ranges from 4.9 to 5.5 percent depending on whether researchers count self-identification, country of origin, or cultural practice. The Muslim population concentrates in major urban areas: in Rotterdam, Muslims constitute approximately 13 percent of residents; in Amsterdam, approximately 12 percent; in The Hague, approximately 14 percent. These communities originate primarily from Morocco and Turkey, reflecting labor migration patterns of the 1960s and 1970s when the Netherlands recruited workers to address postwar labor shortages. Turkish immigration was approximately 500,000 by 2020; Moroccan immigration reached approximately 400,000. These figures include second and third generations born in the Netherlands. More recent immigration from Somalia, Iraq, Syria, and Afghanistan has added religious and linguistic diversity to Muslim communities that earlier consisted primarily of Sunni Muslims from Turkish or Moroccan backgrounds.
Mosque construction and visibility has generated recurring political controversy since the 1990s, reflecting tensions between religious accommodation and secular public space norms. The Netherlands contained fewer than 50 mosques in 1980; by 2023, approximately 475 mosques operated, ranging from converted buildings to purpose-built structures. The Westermoskee in Amsterdam, opened 2016 in a converted Catholic church building, illustrates one pattern of adaptive reuse common in areas with declining Christian congregations and growing Muslim populations. Purpose-built mosques with visible minarets face more complex approval processes: the Essalam Mosque in Rotterdam, which opened in 2010 with two 50-meter minarets, required fourteen years from initial proposal to completion, including court challenges regarding building permits and public consultations regarding architectural integration. Municipal authorities balance religious freedom guarantees in Article 6 of the Constitution against urban planning regulations and neighborhood concerns regarding parking, noise during call to prayer, and aesthetic compatibility. The call to prayer itself exists in legal ambiguity: no national law prohibits it, but noise ordinances restrict amplified sound. Most Dutch mosques do not broadcast the adhan externally, though some have obtained municipal permission for limited Friday afternoon calls. The political party Forum for Democracy proposed banning mosque construction and the call to prayer in 2018, receiving 13.1 percent of votes in the 2021 parliamentary elections.