the whole thing revolves around a magical order, Argenteum Astrum (look it up). The whole purpose of the fraternity can be summed up in one phrase: I Am One. that's what they're after.
i know nobody asked for this... but whatever:
(loose translations. took latin for 3 years and still had to look alot of this up)
portae lucis - to carry shining
azoth - mercury. (consider - source of all metals)
ipsissimus (before beginning) - The highest rank in the Order of the Star & A,',A,',. The ips. is free from all spiritual limitations
adeptus minor (gish) - small attainment or accomplishment
magister templi (siamese dream) - teacher of the temple. (a magister is a teacher, and magister is also 2 ranks below ipsissimus)
magus (pisces) - magical (1st rank below ipsissimus)
opus mago cabalisticum - loosely means "deed of a magical cabalist". (a cabalist is sort of a spiritual wiseman. OMC is also a book -
http://www.esoteric.msu.edu/Archive/Welling.html)
adeptus major (mellon collie) - large attainment or accomplishment
adeptus exemptus (aeroplane) - model or representation of the attainment
theoricus (adore) - meditative or contemplative
practicus (machina) - active. (may refer to adore, meaning it's what SP discovered during adore but put into action. billy has even said something like that before)
philosohpus (machina II) - ...i'm sure you can guess. (could refer to it containing the real or most of the GaTMOG story or message. not sure. maybe something else)
zohar - you pretty much summed it up already, just fit it into this context. the Zohar is where the A,',A,', got all their ranks and stuff. i couldn't figure out if it meant something else, like a rank, but i saw where this was used as a title in a few people's names.
zelator - zealous person or student. (first grade of second order of golden dawn)