The concept of Christian philosophy put forward by Etienne Gilson is a marker used primarily to articulate the fundamental character of medieval philosophy. This paper first affirms the important services done by Gilson, which restored medieval philosophy to its historic standing. Then it examines the meanings of the concept and the historical states of its existence in which Christian belief and reason had got involved in each other. In closing, this article emphatically discusses the scope within which the concept of Christian philosophy can hold good, and in sympathy allows for the possibility of reconstructing the concept by an appeal to some weak rational principle.