The study of social cognition involves the attribution of states of mind to humans, as well as, quite recently, to nonhuman creatures, like God. Some studies support the role of social cognition in religious beliefs, whereas others ascribe religious beliefs to an ontological knowledge bias. The present study compares these distinct approaches in 37 catholic children aged 4 to 10 years, who were administered an adapted version of the unexpected content task assessing false beliefs of different agents: a human, a dog, a robot, and God. The children were also administered an intentionality understanding task, a component of mentalization abilities, and an interview on ontological knowledge assessing emotions, intentions, imagination, and epistemic knowledge. In line with previous research, the results showed that children did not attribute false beliefs to God as they did to the human and to other nonhuman agents. Importantly, while false-belief attribution to the human was associated with the children's ability to attribute mental states (intentionality understanding), false-belief attribution to God was related to children's ontological knowledge. We conclude that, contrary to false-belief attribution to the human and to other nonhuman agents, children's understanding of God's mind is largely a function of ontological knowledge about God, rather than of children's social cognitive functions.