For anticlerical violence in the Spanish Civil War, José M. Sanchez's work The Spanish Civil War as a Religious Tragedy is seminal. Basically, it ticks every box. While the author is Catholic, the book is in no way a polemic against the Republic because the author is careful to minimize his bias. He has a mastery of the literature on the entire war, so he doesn't make any missteps. His research on the motivations for the violence is excellent. His statistical analysis of the killings is revealing. For all that, his narrative is passionate and it draws you in to the stories of the conflict. Then he tops it off by making a complete critique of the Spanish Catholic Church's actions during the war that pulls no punches, and an explanation of the Vatican's actions during the war. It is the gold standard on the subject, and I honestly do not know how it will be surpassed in the future (though it probably will happen, it nearly always does).

I'm sorry, but we don't allow such broad questions here. This would perhaps be best asked in the Thursday Sources thread.