The article examines the relationship between religious values and rational principles of science. The purpose of the study is to identify common grounds of religion and scientific rationality to determine the foundations of medical ethics. The article examines the concept by Kavelin KD in relation to opinions of modern philosophers. Religion educates a moral person and provides guidelines for medical ethics, medicine and scientific knowledge, while science, rational knowledge, clarifies the general conditions of actual existence and provides a tool for arranging a human life. It is concluded that both religion and science display interest in the same task but in a different way. Thus, religion looks at the mental, subjective, and moral side, whereas science is interested in something external and objective.