George Ryskamp, The Spanish Experience in Church-State Relations: A Comparative Study of the Interrelationship Between Church-State Identification and Religious Liberty.” Brigham Young University Law Review 1980:616-653.
This article provides a good basis for the religious freedom your ancestor faced, especially if they were not members of the Catholic church.
This article examines two aspects of Church-State relations: the amount of restriction a church places on individual religious choice and the degree by which a church identifies with a specific religion. Ryskamp makes sure that each concept is examined separately, on a spectrum from total religious freedom to no religious freedom and complete identification to negative identification, respectively. Typically, if a country is moderate in one aspect it is also moderate in the other, while the polarized states (although they may switch sides of the spectrum) are polarized in each case.
Between 1800 and 1869, Spain highly identified with the Catholic church and allowed hardly any religious freedom. Even though various regimes re-wrote the constitution throughout this time, including foreign intervention, heavy church-state identification and religious control continued.
The constitution of 1869 allowed a greater death of religious freedom, implementing civil registration and protecting non-Catholic citizens. The constitution of 1876 took away some of those rights, re-identifying with the Catholic church and restricting any other religious practices.
In 1931, the Second Republic swung to the opposite end of the identification spectrum, pushing hard against the Catholic Church, and thus continuing to restrict personal freedom to worship.
The Franco period from 1936 to 1963 re-established church-state relations. Franco controlled much of the Catholic church, and gave many municipal leaders diplomatic immunity. The Vatican itself, alongside foreign powers opposed this high church-state identification, with the church openly endorsing religious freedom in all countries. It also advocated more democratic processes in determining church decisions. In many ways, the church was able to re-shape itself from its aristocratic nature to become accessible to the working class just as such classes took power. This meant that, until Franco’s death, the church and the state of Spain were at constant odds.
The constitution of 1978 firmly separated church and state, and was passed nearly unanimously, reflecting a changing mindset in both political leaders and the nation in general. It did not completely remove the church from its involvement through culture, but this separation from the government was long lasting.