Dutch society is historically a Christian country. Of the Dutch people who nowadays claim church affiliation, about half are Roman Catholic and half are Protestant. However, only about 20% of the population attends services regularly. The southern provinces of Brabant and Limburg are predominantly Catholic, whereas the other provinces are predominantly Protestant.
If you are looking for a place of worship, here are some suggestions:
Roman Catholic Church
St. Paschalis Baylon, Wassenaarseweg 53, 2596 CL The Hague
Church of St John and St Philip, Ary van der Spuyweg 1, 2585 JA The Hague
Christus Triumfatorkerk, Juliana van Stolberglaan 154, 2595 CL The Hague
Al-Yaqeen, Fruitweg 5-9, 2525 KE The Hague
You can find a more detailed list here.