You want to claim to be Gnostic, then define what a Gnostic is. This should help you:
http://gnosis.org/whatisgnostic.htm
Here is an excerpt from that:
and there is truth to that. Claiming to be Gnostic is no more accurate than when one claims to be Christian. There are many flavors of Christianity and an extremely wide range of tenets and practices through them. Claiming that Gnosticism prescribes hallucinogenic drug use is like saying Christianity prescribes polygyny.
So, what specific branch of Gnosticism prescribes the use of hallucinogenic drugs, not merely allows for them but actually prescribes their use.
Ya see, those SCOTUS issues you posted deal with members of a recognized church and the use was part of their church practices. You, on the other hand, are not claiming to be a member of an organized church and as such, have no claim to established religious practices.