As I understand it, Gnosticism is derived from an understanding/knowledge of the divine. The Heaven's Gate cult based their teachings on the premise that "aliens" were divinities.

It's not too much of a leap to accept that there is some level of contiguity between the two, assuming that man is very different to all mammals. We can then suggest that Man is a variant species inplanted onto Earth by an alien race.

Alternatively, we might consider the "Squareworld" argument (which was briefly discussed in another thread), in that anyone with more "powers" than us might be considered "divine". For example, Thierry Henry, Wayne Rooney, Ronaldinhio may be considered "god-like" in their football prowess. Einstein, Steven Hawkins and other emminent scientists might be considered "god-like" for their mental strengths. An alien race might be considered "divine" for their differentiating abilities - telepathy, space travel etc.

However, the counter-argument is similar to the disproval of belief structures: we have no direct experience/knowledge of the existence of aliens/God; therefore, we cannot KNOW (see arguments on Justified True Belief) that aliens/God exists.

Therefore, the existance of aliens/God relies on faith, rather than knowledge. Heaven's Gate is possibily (to my mind) not Gnostic. However, I do believe Gnosticism is possible and there are logical arguments that allow it - just ones that do not place divinity onto a singular entity.