The comparison of Fundamentalism to Gnosticism "works" on a number of levels.
1) It establishes that the speaker is an expert on both Fundamentalism and obscure things like Gnosticism
2) It compares the enemy (Protestantism) to a group all acknowledge as heretics (even Fundamentalists, hmmm)
3) It points out the role of the doctrine of the Catholic church and its infinite superiority as it beat back the gnostics once and will do it again
1) It establishes that the speaker is an expert on both Fundamentalism and obscure things like Gnosticism
2) It compares the enemy (Protestantism) to a group all acknowledge as heretics (even Fundamentalists, hmmm)
3) It points out the role of the doctrine of the Catholic church and its infinite superiority as it beat back the gnostics once and will do it again
That was my assumption as well.
Although I will say that Gnosticism is alive and well (probably more so than when it began) and I've seen some examples on these threads. I still don't make the connection that I think was implied (but I can't even find the posts you seem to be replying to, so my memory may be faulty).