When the rebellion began (years 1560 and 1570), the overwhelming majority was Catholic or indifferent.Even in the strongworks of Calvinism such as Ghent and the Westhoek, a majority was Catholic. After a clear front line was created between the northern and southern (and eastern) Netherlands, an active protestantiserings policy was conducted in the state area and an active catholicitic politics in the Spanish area, the Contra Reformation.
In the North the Reformed Church became the official church.The big crowd just kept visiting the old church building, even when the pastor suddenly called himself reverend and the statues were taken away. Conscious Catholics went to semi-legal shelters, but for the great masses this was not opportune. Social services such as poor care, education and widows and orphans were only accessible to those who were members of the official church. The majority will not have become a convinced Protestant at one time but have become increasingly protestantser over the course of generations.
In the east and the south, where the Spaniards were up to 1621, the Counter-Reformation managed to strike.This is why Belgium, the southern provinces of the Netherlands and large parts of the Achterhoek and Twente are predominantly Catholic. Subsequent conquests of Spanish territory have no longer led to further protestantisering.
You can see that in the former border area today still many orthodox Protestants live, the Bible Belt.Perhaps in the front area the people were Protestant because the mission of the Counter-Reformation took place next door.
What is often forgotten is that the choice of a religion often has strong politically motivating factors.
For example, if we look at Northern Ireland, the whole conflict is to be traced back to a political choice of Catholic and Protestant.The original religion was Catholic there, and when the English occupied Ulster, the choice of religion was actually a choice for or against a occupying forces.
The same in Poland.Why does the Catholic Church have so much power there? Because Poland was attacked almost throughout history by the Russian Orthodox Russians, the Muslim Turks and the Protestant Germans or the equally Protestant Swedes.
The choice for the Protestant faith in the Netherlands was mainly a choice against Spain.
In addition, I think that the doctrine of Calvin also appealed to the average Dutchman a little more.The austere fit a little more with the also somewhat sober folk nature of the Dutchman.
And the Dutchman wanted ‘ free choice ‘.A foreign power had a single right to tell, what they had to do!
Nice example of how ‘ important ‘ the choice of religion really was for the average Dutchman.Often it was during the Reformation the priest of a church who decided that from that day on the church was a Protestant and not a Catholic church. The majority of believers accepted that without any criticism.
I have no doubt that some priests may have played a more important role than theological motives.
The blood of the martyrs is the seed of the church.We owe this to Charles V and Philips.