Religious robots are robots employed for religious practices and in religious settings. Religious robots can pray with believers, recite religious texts, play religious music, and be utilized in religious education or in religious rituals and ceremonies. Religious robots, compared to other types of robots, are still insufficiently studied, but they are crucial for the discussion on culturally sustainable robotics. Since religion is a part of culture, the question arises as to whether and how robots can be culturally sustainable. In this article, I identify relationality as an important aspect of Christian religion and explore the potential consequences religious robots may have for relationships within Christianity. When discussing religious robots, it quickly becomes clear that relationships are fundamental in religion. People are often concerned that these relationships could be replaced by interactions with robots. I argue that for culturally sustainable robotics, religious robots must consider, preserve, and foster relationships.