Why did so many Germans (including Austria and German Swiss here, Liexhenstein) stay Catholic? For that matter, why did so many Dutch, almost all in Belgium and more than a third in Holland stay Catholic? Why did Luxembourg and most of the whole Rhine area stay Catholic?
Here’s what made places more likely to become Protestant:
more printing presses
more printing competition
proximity to the Protestant strongholds of Wittenberg, Zurich, and Basel
more graduates from the Protestant strongholds of Wittenberg, Zurich, and Basel
distance from the Catholic strongholds of Cologne and Louvain
fewer graduates from Catholic strongholds of Cologne and Louvain
proximity to Protestant princes
not being under Habsburg rule
not having ancient Catholic shrines
high agricultural potential and low populations
no primogeniture
fewer monasteries
I haven’t read the underlying papers, and I don’t know the underlying data especially well, but some of this is straightforward.
Austria, Bavaria, Belgium, and the Rhineland were further from the Protestant strongholds of Wittenberg, Zurich, and Basel, and closer to the Catholic strongholds of Cologne and Louvain.
Austria, Bavaria, Belgium, and the Rhineland were further from the Protestant princes of Saxony and northern Germany. Austria, Bavaria, and Belgium were under Habsburg domination. Austria, Bavaria, Belgium, and the Rhineland had ancient and extensive cults of the saints. They had monasteries. They either had little agricultural potential – Austria, Bavaria – or already-high populations – Belgium, the Rhineland.
I’m not sure about printing or primogeniture, but I suspect that Austria and Bavaria simply had fewer printing presses, and less printing competition, than northern Germany.
it pleases me greatly that access to printing presses is the decisive factor in the choice of religion for millions of people across the generations