In this paper, relying on studies in History of medieval Science, we propose to discuss the teaching of religious facts in secular French school. Starting from a brief presentation of the most significant elements of the debate on teaching religious facts which has occurred in France since 1989, we will then focus on two examples that could feed this teaching; they are both drawn from the History of Science: one is based on the links between mathematics and science of inheritance in Islamic countries and the other one on the theory of the Rainbow.