@Frater INRI said
"Once 8=3 has been really attained, there is no need to revisit previous stages of development."
Every incarnation, no matter what level one has previously attained, one starts all over. "Revisiting previous stages" is exactly what one does. (However, the steps go faster, since it's a recap.)
Remember, there are a new body, a new Nefesh, and a new Rooach to train.
@Selene said
"Does Thelema have a position on monotheism or polytheism?"
Nothing specifically stated that way. There are multiple deities in Liber Legis, and Thelema tends to distance itself from monotheistic religions - but that's not the same as saying that Thelema has a position on the subject.
The A.'.A.'., however, has this to say at the very start:
@Liber LXI said
"Should therefore the candidate hear the name of any God, let him not rashly assume that it refers to any known God, save only the God known to himself. "
@Selene said
"So, does that mean that one can be both a Thelemite and either a polytheist or a monotheist as one chooses?"
In my very humble opinion, yes.