Mind Over Matter

The word "Gnostic" has seen a growing use as meaning either "mind only," or "non-physical." This is not a proper use of the term nor is it useful as a descriptor if this is what you mean.

The words to use are:

Noetic: Purely intellectual; of or relating to the intellect.

Angelism: an approach to humans which does not take into account their bodily nature.

Hidden/Secret Teachings

From the time of the early Heresiological rhetoric untill today, "Gnosis" has been claimed to merely be "secret knowledge." However, this is a blatant misuse of the term.

The word to use is:

Occult: Hidden from view; concealed.  Available only to the initiate; secret.

Inner Teachings

The term "Gnostic" is misused as a descriptor for teachings or doctrines that are limited to an inner circle or group.

The actual word you want is:

Esoteric: Of philosophical doctrines, treatises, modes of speech, etc.: Designed for, or appropriate to, an inner circle of advanced or privileged disciples; communicated to, or intelligible by, the initiated exclusively. Hence of disciples: Belonging to the inner circle, admitted to the esoteric teaching. Opposed to Exoteric.