The Spanish revolution of 1931 that established the Second Republic brought to power a left wing anti-church
http://en.wikipedia.org/wiki/Anticlericalgovernment. The legislation adopted resembled French lacsism.
http://en.wikipedia.org/wiki/LaicismThe government was unable to control the anti-Catholic
http://en.wikipedia.org/wiki/Anti-Catholicsentiment or to curb deadly mob
http://en.wikipedia.org/wiki/Mobattacks on churches and monasteries, during which preists
http://en.wikipedia.org/wiki/Priestand nuns
http://en.wikipedia.org/wiki/Nunwere slain. That caused Catholics (including conservatives and fascists) to muster their forces in opposition, exacerbating the conditions that led to the Spanish Civil War.
However WI the Republican Govt had been more moderate in its management of religious aspects of the constitution? e.g. Not banning religious education in schools, not seizing of church property, not banning religious groups etc. On this basis, the Govt may have thrived turning Spain into an inclusive democratic majority avoiding civil war altogether.
This would then deny Hitler and Mussolini a natural ally in Franco as well as a war by proxy with the Soviet Union. A left wing democratic Spain could also lead to a protracted campaign and occupation by Axis forces in Western Europe during WW2 (especially if Italy became entrenched in Spain as it did in North Africa). It could also attract sympathies from Britain and US (and even the USSR as in the OTL) who may support this fledgling democracy against Nazi aggression directly or indirectly.
Justa thought...
