Presuppositionalism is a school of thought in Christian apologetics that argues the truth of the Christian faith is the foundation for all knowledge. It asserts that everyone has underlying beliefs, or presuppositions, that shape their understanding of the world. For presuppositionalists, the existence of God is a necessary starting point for rational thought and moral reasoning. This approach contrasts with other apologetic methods that rely on evidence or logical arguments to prove Christianity. Instead, presuppositionalists maintain that without accepting the truth of Christianity, one cannot make sense of concepts like logic, morality, or science.