There has been much speculation about this letter of Paul to the
Laodiceans. Some have thought it is what is now called Ephesians, or Philemon,
or even Hebrews. Already by the end of the fourth century there was a
fabricated “Letter to the Laodiceans,” of which only Latin copies survive, but
which was originally written in Greek. It was included in many copies of the
Latin Bible from the sixth century to the fifteenth century. It is a mindless
collection of Pauline phrases, which Lightfoot calls “quite harmless, so far as
falsity and stupidity combined can ever be regarded as harmless.” The most
likely explanation is that the letter Paul refers to here was lost or
destroyed. (Robert G. Bratcher and Eugene Albert Nida, A Handbook
on Paul’s Letters to the Colossians and Philemon [UBS Handbook Series; New
York: United Bible Socities, 1993], 107-8)