On the basis of the research materials, the article provides a brief explanation of the history of the Nestorian religion, compares the vocabulary of the written monument «Nestorian religion» with the vocabulary of the modern Kazakh language, and outlines the obvious differences. In the text, the words are found that still remain unchanged in the modern Kazakh language, and their number is determined. Words are recorded that, despite the small difference, still retain their meaning. At the third stage, the words are decomposed into seven parts of the speech of the modern Kazakh language. In the fourth stage, words are classified by content. Finally, the words that have retained their meaning in the past and in the modern Kazakh language are explained by examples from the text.