Question: who wrote the 21 letters in the new testament
Answer: Collections of related texts such as letters of the Apostle Paul ( a major collection of which must have been made already by the early 2nd century ) and the Canonical Gospels of Matthew , Mark , Luke , and John ( asserted by Irenaeus of Lyon in the late - 2nd century as the Four Gospels ) gradually were joined to other collections and single works in different combinations to form various Christian canons of Scripture .