I'm reading Dylan Riley's [Civic Foundations of Fascism](
https://b-ok.cc/book/5440703/4e76ad) and liking it quite a bit, but one thing that comes out pretty clearly is that while political Catholicism in Italy before and shortly after WWI had an independent and relatively "leftist" streak - lots of independent workers organizations and so on, probably most people reading this are familiar with the PSI/PPI alliance that might have been able to weather through the fascist threat if they could agree over some smaller stuff - Spanish political Catholicism was much more uniformly reactionary and under the direction of local landowners. And this happens despite obvious similarities between the countries - semiperipheral position in world-economy, historical catholicism obviously, very old "republican" associational traditions in the big cities, a liberal political system organized around clientelism and smoke-filled rooms.
When I (or Riley for that matter) try to think of why political Catholicism in Italy would turn against the system, I think of things like "well the state built its power by crowding against the church, which in turn believed it was going to get wiped out by a cabal of freemasons" but that's obviously true of Spain as well, which IIRC actually built up even more bad blood with land reform and so on. And if I think of why they'd be dependent in Spain it's things like "well big landowners used the church to control peasants," and it's not clear why that wouldn't be true in Italy as well - in fact Riley emphasses how in each case local notables organized each initially, but then they became independent in Italy by the 1890s and never really in Spain.
Maybe it's just something like "Italy had higher literacy rates and it's that much easier to self-organize?" But of course it's not like illiterate peasants never get mobilized by the left either.