Catholicism was never banned in The Netherlands. Quite the opposite. The Eighty Years war had a strong religious component in it but the leaders of the revolution didn't want the war of independence from Spain become a religious civil war after the Spanish had gone.

Therefore they added in the declaration of independence an article that made religion a pure personal choice for everybody to make on their own conscience without fear of prosecution. While Calvinism became the official religion of the republic the Catholics but also the Jews were free to practice there religion as long as they did not do that publicly. Which led to 'hidden' churches like https://www.opsolder.nl/en

This also led to a lot of refugees coming from other countries like Jews from Spain and Portugal and Huguenots from France.