[owl57]

Christian context is a bit fuzzy here. On one hand, Monday is called the same in Hebrew (יום שני [yom sheni] = "second day"). On the other hand, Russian "вторник" [vtornik] ≈ "second" is Tuesday, same in other Slavic languages.

[dragonwriter]

Judaism and Christianity both treat Sunday as the first day of the week, so that it is the same in Hebrew is unsurprising.