Why were protestants persecuted by Spain?

Protestants were persecuted by Spain primarily due to the country's strong Catholic identity and its commitment to the Counter-Reformation, which sought to suppress Protestantism and reinforce Catholic orthodoxy. The Spanish monarchy viewed Protestantism as a threat to both religious unity and political stability. Additionally, the Inquisition was employed to root out heresy, leading to widespread persecution of those who deviated from Catholic doctrine, including Protestants. This persecution was part of a broader effort to maintain control and conformity within Spanish territories.