As I've already explained who the Carlist were on a previous posting, I'll try to explain here the meaning of all this catholic symbology, that was very evident on the Carlist units, but also widely used by all the nationalist armies.
For the spanish nationalists who supported Franco, the spanish civil war was a Crusade against atheism and comunism. In fact, they used this name to refer to the war itself: The Crusade.
Like the n**is identification with the Teutonic Order, also the nationalist side used the Crusades as mith to embellish their extreme right ideology. Portraits and posters were made showing Franco and their most important collaborators dressed like a Hospitaliers or Templar Knights, surrounded by Popes, Bishops and all kind of priests, with all the chainmail, the banners and the rest of the paraphernalia and, of course, the Holy Spirit blessing them all. The idea of viewing themselves as a warrior monks were very popular between the sexist and puritan nationalists officers.
To understand how religion played such an important role in SCW, you must realize that Catholicism was at the deepest roots of Spanish culture and tradition. The Inquisition was not abolished until 1820, and the practice of torture to extract witchcraft confessions was allowed until 1834.
The Catholic Church was immensely rich, possessing enormous extensions of land, countless buildings like monasteries, churches, schools, palaces, manors... and large quantities of jewelry and precious metals in the form of objects of worship and works of art. All this without paying taxes to the State (this is still the case in 2021 ...!!) and always siding with the powerful and never the oppressed.
Its influence on education was essential, as, until the triumph of the Republic, Spanish governments never had education among their priorities and provided only a low-quality primary school, leaving teaching on the hands of Catholic schools for those who could afford it. This is for boys, because for girls, in addition to reading and basic math, education was geared towards making them good, obedient wives. This in a country where, by 1931, 50% of children did not go to school and where 28% of the population was illiterate.
Local priests exercised obscene power over their communities, denouncing on Sunday sermons fellow citizens who disliked them, giving names, making public intimate or private acts, whether truth, mere rumors or pure defamation, provoking social isolation from those who did not follow its precepts (this, I have seen with my own eyes and I was born in 1960 ...). That is why the Catholic Church was so hated among the workers, the peasants and all the liberal and free-thinking people.
I hope you can better understand the role that the defense of Catholicism (or hatred against) played in events related to previous years and the war itself.
As much as you seem to like personal contributions, my father’s uncle was minister of education, after agriculture and after education again, for various left-wing governments in the Republic.