Christianity on the whole is declining in the Netherlands.
As of 2015, over half the county claims no religious affiliation.
Per those same statistics, Protestantism has declined from about 60% in the mid-20th century, to about 20% now, less than the number of those claiming Catholic affiliation.
The largest Protestant denomination, the PKN, embraces religious “pluralism”; 42% of members are non-theist, and 1 out of 6 clergymen are agnostic or atheist.