This study is about a King of Sweden and his relationship to Martin Luther’s theology. Gustavus III was king in Sweden during the 18th century and he is mostly famous for being a friend of the theater and arts. This study investigates the religious relationship between the king and the image of Martin Luther’s theology. My main question in this study asks how Gustavus III described himself as a Lutheran Monarch. The method consists of a content analysis of primary sources from the late 18th century, mainly Helgdagsreduktionen from 1772 and the Eccelesatique-samlingar from 1789. The result shows that the King had churchly ambitions and was interested in liturgical questions. The result also shows Gustavus III worshipped former kings of Sweden which influenced how the king wanted to describe himself as a good Lutheran in the shadow of Gustavus I and Gustavus Adolphus. The household theology of Martin Luther shows the position of the king and how he absorbs this position in his writing to the subjects and the priests. The king’s function is viewed as a father that maintained the subject’s true path to Christianity. The image of Gustavus III is also central in this study because the idea of the early modern monarch was forged in the very foundation of the protestant reformation which Martin Luther started.