Final answer:
The incorrect reason for why Paul's letters were read out loud is that it was a formal practice. Instead, it was due to practical needs such as illiteracy, affordability of manuscripts, and ensuring that all could hear the message. The correct option is 4) it was formal to do so
Step-by-step explanation:
Among the reasons why the letters of Paul were read out loud, the one that is NOT a reason is that it was formal to do so. This option is incorrect because, in the context of the early Christian churches, formalism was not the driving factor behind the practice of reading letters aloud.
Early Christian communities often included many members who could not afford their own manuscripts and some members who could not read at all.
Additionally, reading aloud allowed everyone assembled to hear the message, as private reading was less common at the time. Therefore, the practice was born out of practical necessity rather than formality. The correct option is 4) it was formal to do so