the Epistles (New Testament)
Refers specifically to the letters in the New Testament, such as those by Paul, Peter, John, etc. Used in Christian contexts.
新約聖書の使徒書を読む。
I read the Epistles of the New Testament.
Compound of 使徒 (apostle) + 書 (writing, book). The exact historical derivation is uncertain, but the term is conventionally used for the apostolic letters in the New Testament.