Spain has been along history one of the main defenders of the Catholic doctrines and have tried to spread them all over the globe, in the colonies they had established during the Empire times and also to defend it from disidence of heresy within their territories, at any cost.
Inside their territory, Spain did not admit heretic behaviours. This is how the group of institutions known as The Inquisition was founded in the 12th century, to combat heresy when it was detected among baptized Christians. They arrested suspects, tortured them until they confessed and prosecuted them in the Inquisition courts. Many times, when it was decided that someone was guilty, this person was burnt alive.
The index of forbidden books listed those that were considered heretic, and were therefore banned for true Christians. Someone that was found reading one of the forbbiden books was arrested by the Inquisition.
The Inquisition lasted until the 19th century, when it was abolished after the Napoleonic Wars.
