To
sbroadway:
Willingness of adherents to die for an idea is a rather odd factor to be considering, especially at a time when there are no shortage of folks willing to give up their lives for religious ideas we find abhorent. Even ignoring extremists, groups like Falun Gong have more martyrs than they can count, but in all instances these amount to a test of the individuals dedication against institutionalized adversity, not a test of the doctrine's validity.
There are plenty of intelligent critiques of gnosticism (and pop-culture neo-gnosticism especially), but "followers are not willing to give up their lives for it" isn't one of them. Its also worth noting that in the past gnostic sects endured far more than their fair share of persecution.