In the article based on the Siberian materials of the 19th-21st centuries, a way to solve the problem of understanding the foundations and characteristic features of the Russian Orthodox architecture as a way of expression of religious ideas of an ethnos and society is proposed. The proportional-metrological system and the figurative-symbolic structure of the churches are considered as indicators of the essence of foundations of the cult Orthodox architecture. The conducted review of the scientific literature showed that the largest number of studies was done on the materials of Ancient Russia, only a few works are devoted to modern structures, and there are few works done on the Siberian materials. Publications concerning the “golden section” in the church architecture were revealed. The problem offoundations ofproportioning, symbols and images in the temple architecture is still far from being solved, experts have not yet come to a consensus. There are no generalizing and systematizing scientific works on this topic, although there is an extensive relevant source base. An original set of approaches and methods is proposed that allows solving the problem, which includes general scientific methods and methods of individual sciences using the advantages of an interdisciplinary approach. The research arsenal includes methodological techniques of ethnography and other historical sciences (direct observation, historical-genetic, typological, relics, case-study, hagiographic), history and theory of architecture (identification of proportional compositional features of buildings and structures, metrological structure, construction methods dimensional drawings, the original author’s method of analysis of proportional-metrological features of buildings and structures), informatics (the use of computer programs for processing primary data and the formation of resulting images and drawings, the author’s automated method of variant modeling). The conclusion is made on the possibility of solving the set problem.