A peculiarity of Russian religious landscape is high number of the Russians identifying themselves with Orthodoxy – a fact accompanied by low indices of actual religious practice. This circumstance defines a need to develop and clarify sociological tools to provide clarity for strictly religious type of believers, characterized by high level of religious involvement and direct connection of religious consciousness with practical behavior. The article presents analysis of the validity and heuristic potential of V-Index methodology (“enchurchment index”) that is traditionally used in Russian sociology to study Orthodox religiosity. Within the empirical analysis, the data were used that had been obtained from the project “Religious knowledge, beliefs, and practices in life-world: interconfessional peculiarities (Orthodoxy and Protestantism) supported by the Russian Foundation for Humanities (№ 11-33-00381). The results indicate that V-Index scales work perfectly well for studying Orthodox religiosity. These scales characterize frequency of going to church, participating in the Eucharist, reading the Holy Scripture, as well as the form of prayer and church fasting. There is the evidence that the ways of categorization, applied within the ”classical” form of V-Index and even in its more strict modification, do not allow to emphasize more distinguished groups of believers that would be described by the association between the religious behavior and consciousness. These criteria include into the strongest group the respondents who do not share the most significant religious statements. The other ways of categorizing, based on the minimization of the root-mean-square deviation, principles of the “weak response” and the “number of strong responses” are quite close. With their help, it is possible to distinguish groups of believers characterized not only by high level of involvement into church life, but also by the Christian consciousness. The results of the research allow us to state that there is unconditional connection between five variables used in V-Index, that reflect the Christian lifestyle, and variables characterizing religious knowledge and beliefs. This is why the use of characteristics of religious practice alone is still enough and allows to provide the ground for religiosity criterion. The regressive analysis has allowed to distinguish three most significant variables for identifying a strictly religious type: frequency of participation in Eucharist, observation of church fasting, and reading the Bible. These variables can be used for an express-diagnostics in various studies of Orthodox religiosity.