The Centrality of Religiosity Scale (CRS), the Francis Scale of Attitude towards Christianity (FAC) and the Post-Critical Belief Scale (PCB) are three prominent measures of religiosity. Comparing the three measures on theoretical grounds, one may assume that high religiosity (CRS) is linked to both a strong attitude towards Christianity (FAC) and to orthodoxy (PCB), while no religiosity (CRS) may be associated with both a low expressed attitude towards Christianity (FAC) and external critique (PCB). This paper examines that assumption on the basis of a convenience sample of N = 4.396 participants that filled in an online questionnaire (age: M = 47; SD = 15.90; 47% females; denomination: 1226 Roman-Catholics, 2369 Protestants, and 801 participants that have left the Roman Catholic or Protestant church). Factor analysis supports the one-dimensional structure of CRS and FAC. Exploratory factor analysis reconstructs the two-dimensional structure of PCB. There is a very high positive correlation between CRS and FAC (r = 0.92), indicating that CRS and FAC measure the same issue within a Christian context. Moreover, CRS and external critique of PCB correlate heavily negatively (r = −0.83). Finally, there is a very moderate negative correlation between CRS and relativism (r = −0.26). Multiple regression analysis reveals that both factors predict much of CRS (R2 = 0.75) or FAC (R2 = 0.83), while age and gender are of minor impact. Region, education, and income do not predict the outcome of CRS or FAC at all. This result will be discussed.