<p>The Heidelberg Catechism was one of many catechisms that originated during the 16th-centuryReformation. It is also known that the authors of the Heidelberg Catechism made use of existingcatechisms. The content of 16th-century catechisms consisted mainly of the Decalogue, theApostolicum and the Lord’s Prayer. The Heidelberg Catechism starts with the famousintroduction, dealing with man’s only comfort, and in three sections with knowledge of our sinand misery, knowledge of our deliverance, and knowledge of how we should be grateful forour deliverance. This contribution points out that the threefold structure of the HeidelbergCatechism is not unique, but appeared in different ways in different catechisms of prominent16th-century refor...