>>Are not many of the ideas now attributed to gnostic teaching much
older than early Christianity...and even older than Judaism?<<
Not in the more strict usage of the term "Gnostic". Of course, on the
other hand one could argue that there is nothing new under the Sun
and pretty much any idea from any movement has some origin in a
movement before it.
Since some essential parts of Gnostic teachings are Platonist those
parts certainly existed before Christianity. Since some elements of
Judaism existed before Judaism and some of those elements are
expressed in Gnostic texts, then those elements existed before
However, the fact that modern America has important cultural and
ideological (and even indirect historical) connections with Rome
doesn't imply that modern Americans ARE Romans. The Gnostics
themselves don't predate Judaism or Plato.