Compulsory Schooling Laws and Formation of Beliefs (?) - Research Paper

While I find the initial results from this paper appealing (confirmation bias?), Pogorelova and Mocan's "Compulsory Schooling Laws and Formation of Beliefs: Education,Religion and Superstition" does present me with some questions. Abstract below:

"We exploit information on compulsory schooling reforms in 11 European countries, implemented in the 1960s and 70s, to identify the impact of education on religious adherence and religious practices. Using micro data from the European Social Survey, conducted in various years between 2002 and 2013, we find consistently large negative effects of schooling on self-reported religiosity, social religious acts (attending religious services), as well as solitary religious acts (the frequency of praying). We also use data from European Values Survey to apply the same empirical design to analyze the impact of schooling on superstitious beliefs. We find that more education, due to increased mandatory years of schooling, reduces individuals’ tendency to believe in the power of lucky charms and the tendency to take into account horoscopes in daily life."

The 11 countries under study for religiosity were Austria, Belgium, Denmark, France, Great Britain, Greece, Hungary, Ireland, United Kingdom, Poland, Spain, and West Germany (for the horoscope analysis they only used Austria, France, Greece and Germany). Other countries were not included for methodological reasons. These countries actually give us a wide European cross-section, from Catholic to Protestant and Orthodox, from dictatorships or under Soviet control (at the time of the reform) to democracies, from northern Europe to the Mediterranean. And yet, we have to be careful in extrapolating to non-European contexts (a large gains schooling in Africa and Asia are due to religious schools)

 Firstly, I would say that the study measures religious practice rather than beliefs, unless you count in superstition (depending on your view of religion), that measures both belief and practice. 

It measures two very specific cohorts, maybe it should also do a comparison with overall trends in religiosity or with younger and older cohorts. The period under-study was a major turning point for the Catholic Church (many of the countries analyzed have large Catholic populations) with the Second Vatican Council, that changed rules and norms among Catholics on religious practice and to this day still has open discussions. The Council itself was a response to calls to modernization (and maybe address a trend that the study correlates with schooling)
 

Another point to note is that in many of the countries studied, religious institutions are/where important providers of schooling at the time of the reform. The reform itself could have diminished the influence of religious providers either because of expansion of public schools (I know in Spain the reform was coupled with a wave of school construction), the lack of capacity to actually cover the extra (or two) years of schooling or actual decline of religious/denominational schools (the number Catholic schools in Europe declined 18% between 1975 and 2000)

Measuring superstition is always a tricky affair, are lucky charms and horoscopes (in four countries) sufficient indicators? 

How does schooling and religiosity correlate with other values or beliefs? nationalism, conservatism, capitalism, belief in aliens, etc..?

HT to Chris Blattman