This article is from the World English Bible Translation FAQ, by Michael Paul Johnson firstname.lastname@example.org with numerous contributions by others.
Because the Greek New Testament was written not in the formal
written register of the language, but in the informal register of
the language used by common people, we have decided to use the less
formal spoken register of the English language. This sounds much
more natural when read aloud. The primary difference noticeable
between spoken or informal written English and formal written
English is the greater use of contractions.