Catechism primers are inconspicuous but telling little books for children combining the teaching of reading skills and religious catechesis. From the 16th to the 19th centuries, they have been produced, disseminated and used in huge numbers in many regions of the world, in particular in Europe. Remarkably, similar texts appeared across the continent, spanning confessional traditions that were in other respects highly divergent. In different places, and across the whole period, different denominations used not only similar pedagogical and religious strategies, but also shared the same formats...