clipped from: coloquio.com   
Plutarco Elías Calles

Calles was inaugurated on November 30, 1924, and lost no time plunging Mexico into the most severe religious crisis of her history. The 1917 Constitution contained articles which practicing Catholics considered intolerable -- among them were provisions outlawing monastic orders, prohibiting religious organizations to own property and reducing clergy to the status of second-class citizens by taking away their right to vote. Obregón disliked Catholicism but was a practical man who followed a policy of applying the articles selectively -- with rigor in areas where the Church was weak, leniently or not at all in regions where the Church was strong.

Calles, by contrast, was a fanatic determined to extirpate every trace of Catholicism from Mexico. On June 14, 1926, he signed a decree known officially as "The Law Reforming the Penal Code" and unofficially as the "Calles Law."