Before and after the rise of Christianity, philosophers depended largely on developing axioms and using them to draw conclusions about the world. Before Christianity, axioms were typically based on what was evident to human reason. After the spread of Christianity, thinkers had to deal with a new source of knowledge, based on faith rather than on what seemed obvious to the human mind. Early Christians justified their dependence on faith in different ways. Some embraced fideism and favored faith even without or over reason. Others have made the effort and fused their new traditions with older ones. Thomas Aquinas describes and responds to several challenges to Christianity. Aquinas states that the study of God revealed in Christianity, which he calls Sacred Doctrine, is a science that begins with divine revelations as axioms and uses human reason to construct a significant body of information about who God is and how human beings they should behave. Aquinas goes on to respond to the challenge that if Christian-based philosophy is a science, it is a lesser science because it is less certain of its conclusions, having accepted them on faith. Aquinas responds to this argument in two parts. First, he argues that God's revelation is more certain than what seems obvious to humans because God, unlike humans, is omniscient. The only reason it seems less certain is because fully understanding God's level of certainty is beyond human capabilities. Aquinas's second response is that the Sacred Doctrine deals with more important topics than other sciences and is therefore more important. All other sciences, he argues, indirectly seek the same goal, eternal bliss, that sacred doctrine seeks directly. It's worth nothing... middle of paper... assuming that because he experienced the idea of ​​perfection, God must exist. Nonetheless, Descartes was able to provide evidence, if not proof, that God exists and is responsible for the clear and correct aspects of human reasoning. The rise of Christianity raised questions about how this new way of thinking, based on faith, could adapt to and interact with a world that had not based its thinking on faith but on human reason. While some rejected the compatibility between the new and old ways of thinking, others sought and found ways to reconcile both ways of exploring the world. The traditional philosophical method of starting from assumptions that cannot be proven but are assumed to be true and progressing to conclusions based on those assumptions was applied by both Aquinas and Descartes to address the mutual challenge posed by Christianity and philosophy.