Learn Russian: Его главная заслуга в том, что он выбрал монашеский путь. - His main merit is that he chose the monastic path.

In Russian, abstract nouns like заслуга (merit) often need a grammatical "bridge" to connect to a subordinate clause. Because the underlying phrase is заслуга в (merit lies in [something]), the prepositional pronoun том acts as a placeholder for the clause: заслуга в том, что... (the merit is in the fact that...). English just says "is that," making this a common trap for learners.

Путь is a masculine noun. Why does its declension pattern trip up so many learners?

Путь (path/way) is highly irregular because it is a masculine noun ending in -ь that declines almost exactly like a feminine third-declension noun (such as тетрадь). It takes the ending -и in the genitive, dative, and prepositional cases, with its only masculine-style ending being the instrumental путём. Here, it is in the accusative case, which safely matches the nominative.

Could I translate "merit" as достоинство in this sentence?

Not quite. While both can translate to "merit" in English, their Russian meanings are strictly divided. Заслуга refers to a concrete achievement, a contribution, or something earned through active effort (like choosing a difficult life path). Достоинство refers to an inherent positive quality, an advantage, or personal dignity.

How is the adjective монашеский formed from монах (monk)?