Religious nationalism is a political ideology that seeks to establish and maintain a close alignment between religious identity and national identity within a particular geographic area and community. Religious nationalism is characterized by the belief that a specific religion and religious tradition is not only integral to the cultural and historical identity of a nation but also serves as the fundamental basis for defining and organizing the nation-state. In accordance with these findings, this article focuses on the research of post-Soviet scientists regarding the concept of religious nationalism. The concept of religious nationalism as a whole has been little studied, not only by domestic researchers but also by scientists in the post-Soviet space. When searching for the keyword “religious nationalism” in the Web of Science Core Collection, we could not find studies conducted by domestic scientists. We found nine scientific works in which this concept was used among post-Soviet scientists. The first section of the main part of the article describes the research of Russian scientists. The second section analyzes the views of Armenian and Lithuanian scientists. As a result, among the joint author’s works with authors from one country and scientists from other countries, we paid special attention to the research of six Russian scientists, two Lithuanian scientists, and one Armenian scientist. Russian scientists pay attention to the problems of religious nationalism in their country in 4 articles; Armenian scientists in 1 article. Lithuanian scientists analyze the problems of Eastern and Central Europe. The article identifies several reasons why scientists in the post-Soviet space rarely study religious nationalism. We have touched on some pressing issues in understanding religious nationalism. In addition, in the process of systematizing the research of scientists, it was found that there are several common points of view.