While Paris had a sizable Jewish population, Protestantism was also practiced, and other religions existed, Catholicism was the dominant faith in both Paris and France as a whole.
It's important to note that:
* The French Republic was officially secular at the time, meaning the state didn't favor any religion. However, Catholicism remained deeply ingrained in French culture and society.
* The Catholic Church had a powerful influence on many aspects of life, including education, healthcare, and social services.
* Religious tolerance was generally practiced in Paris, but anti-Semitism and other forms of discrimination were not unheard of.
If you'd like to learn more about the religious landscape of Paris or France in 1870, I can provide you with additional information and resources.