Final answer:
The 5-letter word referring to authoritative religious texts is 'Canon'. The Torah is central to Judaism, while the Qur'an serves as the holy scripture in Islam.
Step-by-step explanation:
The 5-letter word that refers to the set of books that have authority in a religion is Canon. This term is used across various religions to describe the officially accepted collection of texts. For example, in Judaism, the Torah is considered the most holy text, containing the first five books of the Bible. In Islam, the holy scripture is the Qur'an, which is believed to be the word of God as recited by Muhammad. Each of these sacred texts plays a pivotal role in the respective religions, shaping beliefs, practices, and the daily lives of its followers.