Haha... Here's a task for frequency nerds, describe your spirit as a linear system transforming divine signal to human thought, draw up its poles and zeroes, and its Nyquist diagram.

I guess "frequency" as a word may have been adopted by the New Age community due to its association with color. However, I think it's problematic, due to its association with time. Going into woo-woo spiritual mode for a moment, my current perception / belief is that "higher" or "outer" layers of our existence are beyond the timeline of this physical universe (as in the timeline appears as a single static object from the outside).

The pineal gland stuff is definitely suspect. I kinda rank it as an outdated popular myth, along with 'ectoplasm' and the spiritual properties of radioactivity.  A spiritual thinker / guru can, though, definitely say valid and true teachings while (through cultural contagion) also regurgitating some of this dumb stuff. I mean, from a viewpoint of spirit, frequencies and pineal glands are meaningless, one could equally talk about "higher and lower acidity" and receiving spiritual information through your little toe, and it wouldn't make a real difference.