The author of the article applies synchronic and diachronic approach to describe consistent patterns in Russian word formation, when the facts in contemporary Russian are explained with due regard to the history of their development and formation. The research focuses on commonly used derivatives of the Church Slavic, which have not lost their sacred meaning despite the general secularization beyond religious discourse of evangelic lexis in Russian (as well as in other Slavic languages). The preservation of the sacred meaning is influenced by a specific process of differentiation between the sacred and the secular by means of wordbuilding formants in cognate synonyms (for example, Рождество [‘Christmas’]/рождение [‘birth’]; житие [‘the life (of a saint)’]/житье [‘ordinary life’]; Воскресение [‘Resurrection’]/воскресенье [‘Sunday’]; искупить [‘to redeem’], Искупитель [‘the Redeemer’]/выкупить [‘to buy out’] etc.). The last section of the article considers the process of semantic specification in diachrony of originally synonymic cognate derivatives like живот [‘belly’], житие [‘the life (of a saint)’], жизнь [‘life’], which has led to a complete change of the semantics of the lexeme живот [‘belly’] (a gradual strengthening of its physical component has led to the modern meaning ‘belly, part of body’) and the prevalence of the word жизнь (with its Old Slavonic suffix знь). The latter, having absorbed the “liferelated” semantic of lexemes живот ‘belly’ and житие ‘the life (of a saint)’, expresses all aspects of its understanding and interpretation by the contemporary language community. The author assumes that this process could also have been influenced by the general correlation between the Church Slavonicisms (both elevated and general denominations) and native Russian words (both concrete and ordinary denominations) in Russian. Wordbuilding formants play a significant role in the differentiation of the sacred and the secular (and preserving the sacred) when the religious lexicon of the Church Slavonic origin enters the modern Russian language.