Actually, there are many "beginnings" in the scriptures. It is context that
determines which beginning is referenced. For example, we have Acts 11:15:
KAI EF hHMAS EN ARCH
Acts 11:15 But when I started to speak, the holy spirit fell upon them just
as it did also upon us in [the] beginning.
We add [the] here, but is it the _absolute_ beginning? Or merely a
reference to Pentecost, the beginning of their spirit anointing? The
addition of the English [the] does make for better English.
I might second Carl's idea that the John 1:1 EN ARCH is merely a reference
to the beginning of the heavens and earth, or _perhaps_ the beginning of
the "coming into existence" of the TA PANTA in v. 3.
Sincerely,
Wes Williams
P.S. After a quick check, I also found some unqualified EN ARCH references
(without a genitive) in the LXX (cf. 2Sam 17:9, which is not an absolute
beginning; Prov 8:23 [which I do not recall ever discussed on b-greek]).