Carantanians were the first Slavic people to be Christianized and missionaries were faced with a thoroughly new field of work. Thus missionaries both in Carantania and Pannonia encountered substantial difficulties in their work, the adoption of a new religion was an enormous challenge also for gentile-religious societies. The paper draws attention to the difficulties and strategies of setting up linguistic communication, which is a prerequisite for Christianization, the importance of Christianization from above, and the importance of missionaries arriving as guests rather than as intruders. The paper discusses the integrating role of Christianity along with societal changes that were associated with the arrival of Christianity in gentile-religious environments