ANSWER: Origin of the Phrase "Ideas are Bulletproof."

I've had a great time trying to track down the source for the phrase "ideas are bulletproof."

One clear attribution-- and probably the one that has led to the phrases current popularity-- is to Alan Moore in either the original Warrior comics or in the 1989 book "V for Vendetta." The original form seems to be:
"Did you think to kill me? There's no flesh and blood within this cloak to kill. There is only an idea. And ideas are bulletproof."

It was made into the 2005 film of the same name. The film version is:
[after a hail of gunfire doesn't stop V]
Creedy: Die! Die! Why won't you die?... Why won't you die?
V: Beneath this mask there is more than flesh. Beneath this mask there is an idea, Mr. Creedy, and ideas are bulletproof.

However, "V for Vendetta" is known for its intertextuality. It is full of unattributed quotations.

A search of quotations databases retrieves these related ideas:

"There is one thing stronger than all the armies in the world; and that is an idea whose time has come."
[in Nation 15 April 1943]

from:
"Sayings and slogans" The Oxford Dictionary of Modern Quotations. Ed. Elizabeth Knowles. Oxford University Press, 2002. Oxford Reference Online. Oxford University Press. SUNY Buffalo, Lockwood Memorial Library. 8 June 2006

AND

Hugo, Victor 1802-85

"A stand can be made against invasion by an army; no stand can be made against invasion by an idea."
[Histoire d'un Crime (written 1851-2, published 1877) pt. 5, sect. 10]

from:
"Hugo, Victor" The Concise Oxford Dictionary of Quotations. Ed. Elizabeth Knowles. Oxford University Press, 2003. Oxford Reference Online. Oxford University Press. SUNY Buffalo, Lockwood Memorial Library. 8 June 2006

The two above links work from SUNY Buffalo. You may have online access from your local public library or from some other source.