If Cecil can make an old column appear http://www.straightdope.com/classics/a990326.html
Then it’s only fair to conjure up cmkeller’s original column of comments http://boards.straightdope.com/sdmb/showthread.php?threadid=135
For a bonus, Cecil made an appearance in cm’s comments column.
From what I read, Abracadabra is a distortion on ABRAHADABRA. (Aleph, Beth, Resh, Aleph, Heh, Aleph, Daleth, Aleph, Beth, Resh, Aleph). This word is used in Qabalah to represent the Great Work. Many interpretations can be found in 777 by Aleister Crowley.
I agree with Cecil’s sources that “Abracadabra” originated
in Gnostic magic. However, his description of Gnostics as
Christians is incorrect, or at least oversimplified.
Some Gnostics were also Christians. But some were not.
Gnostic ideas influenced many religions of the late classical period,
including not only Christianity but various now-extinct pagan cults and Judaism
as well. (The “Merhavah” tradition of Jewish folk magic
that later evolved into Kabalism shows strong signs of Gnostic influence.)
I’d go even further and say that some Gnostics had picked up some vaguely Christian terminology and Christian brand names. Their essential beliefs are absolutely and utterly at odds with Christian theology.
(However, I have to be careful, as the word “Gnosis” actually means only “Knowledge”, and at least one Christian writer, Clement of Alexandria, tried to co-opt the word by calling Christianity “the true Gnosis”.)