I saw this on the CoS site, and now I am a little confused:
Registered Member (no degree)
Active Member—Satanist (First Degree)
Witch/Warlock (Second Degree)
Priestess/Priest (Third Degree)
Magistra/Magister (Fourth Degree)
Maga/Magus (Fifth Degree)
“Administrator,” “Agent,” and “Grotto Master” are descriptive titles for what people do, not levels of rank, thus they can can be held by members with different degrees. “High Priest”/“High Priestess” are the top administrative titles, and can be held only by Fourth or Fifth Degree members.
Those who hold the Third through Fifth degrees are all members of the Priesthood of Mendes and individuals with these titles may be called “Reverend.”
Does this mean that it is acceptable to address, say, a Magister as either 'Magister' or 'Reverend', or is Magister a title only, with 'Reverend' the correct form of address?