Why did Johannes Kepler originally plan to become a theologian?

Johannes Kepler originally planned to become a theologian because he was a beneficiary of a ducal scholarship system in Germany designed to train poor boys for service to the state and church. As a student at the Lutheran Stift (seminary) at the University of Tübingen, it was expected that graduates would pursue careers as ministers, schoolteachers, or state functionaries.1

Although Kepler’s career path shifted toward astronomy, he maintained a profound sense that his vocation remained a religious one. He viewed his scientific work as a way to demonstrate the divine plan written in nature, famously remarking that he was satisfied to "guard the gates of the temple" in which Nicolaus Copernicus made sacrifices. He eventually came to see his astronomical efforts as a means through which "God is being celebrated".12