The article presents the concept of a comparative dictionary of biblical expressions of the East Slavic languages. The dictionary research project is being implemented by the members of the phraseological seminar of St Petersburg University under the guidance of Professor Valery Mokienko. The purpose of the designed dictionary is to reflect the international character of most biblical winged words and expressions, as well as the specifics of the phrases that arose in each of the East Slavic languages on the basis of biblical plots and images. At the moment, this material has been only fragmentarily studied in a comparative aspect and requires large-scale lexicographic development. Russian, Belarusian, Ukrainian Christian texts (Old and New Testaments, non-canonical apocrypha and legends), monolingual (East Slavic) and multilingual dictionaries of biblical texts were sources of material for a comparative dictionary; examples of the use of these units in modern speech were selected in the national corpora of Russian, Belarusian and Ukrainian languages, on Internet media sites, on social networks, in messengers (2020-2024). The formed material bank includes more than 2 thousand correlative biblical words and expressions in three East Slavic languages. The results of the historical-typological, structural-semantic and contextual analyses of this material are presented in the corresponding parametric zones of dictionary entries, which is shown by examples. The comparative method made it possible to State the similarities and differences of the correlative units in the three languages, which are reflected in the dictionary entry by particular graphic signs. Special attention is paid to the semantic development of biblical expressions: the article presents a lexicographic model of the comparative reflection of their polysemy. The authors' point of view on the issue of innovative parameters of the dictionary is argued: the expediency of including records of dialect Speech refiecting folk interpretations of the biblical text in the illustrative zone of the entry is proved. The possibilities of placing and commenting on biblical expressions' modern transformations, which are ambiguously evaluated by linguists, in a special parametric zone of the entry are also shown. It is emphasized that the projected dictionary will fill a gap in the East Slavic biblical lexicography, provide valuable linguistic and cultural material to researchers of the East Slavic language space, and also become a useful reference source that will serve to enhance the culture of Speech and a deep understanding of the biblical linguistic heritage by native Speakers of the East Slavic languages.