So much for those "Conservative CAtholic" Mexicans we've all been hearing about who will save CAlifornia from liberalism.
Dittos
You're confusing the religion of many Mexicans with the politics of the government. The favorite pastime in Mexico since Independence has been the sport of gelding the Church.
The law was promoted by Coahuila's Institutional Revolutionary Party, which rules the state.
Look what happened back in 1926 when the Catholics decided they wouldn't take it anymore: The Cristero War.
Something like 90,000 people from both sides died. The country is Catholic. The government is not.