The study is devoted to the religious vocabulary in the dialects of the Old Believers in order to identify confessional and dialectal characteristics. The novelty of the research lies in the fact that for the first time a description of the religious vocabulary of the Old Believers-chapels of Latin America is carried out. A review of scientific literature has been carried out, which describes various aspects of the study of the religious vocabulary of the Russian language, including dialects. The relevance of the work is due to the need for theoretical comprehension and differentiation of the concepts of “religious vocabulary” and “confessional vocabulary”. The author’s definition of the term “religious vocabulary” as a hyperonym in relation to the terminology related to the sphere of religion is given. The material was written texts of the Old Believer Danila Zaitsev. Semantic and contextual analysis, comparative analysis of the semantics of Old Believer religious terminology relative to Christian terminology, as well as the linguo-theological method were selected as research methods. A new approach to the classification of religious vocabulary is proposed. It is concluded that four groups are distinguished in the vocabulary of Old Believer’s dialects: common vocabulary in a religious sense; common Christian vocabulary in confessional discourse; confessional vocabulary as a marker of a specific confession; confessional and dialectal vocabulary in Old Believer dialects.