" In his own Alexandrian context, Philo sets a middle course between the literalism of groups like the Sadducees, on the one hand, and the reform position of those he calls "extreme allegoriziers," on the other. Apparently Philo knew and disapproved of a group of Jews who took allegory so far as to maintain that it (question: it is allegory or to oberseve Judaism?) was no longer necessary to observe Judaism; it(question; what is it here?) was necessary only to understand the moral virtues that were represented and advocated by the biblical allegory:

There are some who, regarding laws in their literal sense in the light of symbols of matters belonging to the intellect (question; the meaning of this phrase and what is the matters belonging to the intellect? ), are overpunctilious about the latter, while treating the former with easy-going neglect, Such men I for most part should blame for handing the matter in too easy and off-hand a manner: they ought to have given careful attention to both aims, to a more full and exact investigation of what is not seen and in what is seen to be stewards (question; is steward used here as figure of speech? Could you explain the meaning of this phrase?) without reproach, As it is, as though (question; the meaning of as though) they were living alone by themselves in a wilderness, or as though they had become disembodied souls, and knew neither city nor village nor household nor any company of human beings at all, overlooking all that the mass of men regard, they explore reality in its naked absoluteness. These men are taught by the sacred word to have thought for good repute(question; Are they considered as tending to repute?) , and to let go nothing that is part of the customs fixed by divinely empowered men greater than those of our time."

(from Rebecca's Children)
I find this type of reading almost impossible to understand.

However, I can answer one key question.

It is necessary ... The "it" does't refer to anyting in the sentences. It means "one must"

It is not necessary to -- a person (any person) doesn't have to...
eunjinny, There's not enough room In the space provided here to answer your question(s). May I suggest you contact a practicing Rabbi for a detailed exegisis? Also, I believe you'll find the term is JUDAISM
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 BarbaraPA's reply was promoted to an answer.
Thank you, that would be great.