The interplay between religion and the economy has long occupied social scientists. We construct a unique panel of income and Protestant church attendance using 175 Prussian counties, presented in six waves from 1886 to 1911. The data reveal a marked decline in church attendance coinciding with increasing income. The cross-section also shows a negative association between income and church attendance. The associations disappear in panel analyses, including first-differenced models of the 1886 to 1911 change, panel models with county and time fixed effects, and panel Granger-causality tests. The results cast doubt on causal interpretations of the religion-economy nexus in Prussian secularization.