Rightly dividing
the word of truth as quoted from
ll Timothy 2:15,
is not to divide the Testaments.  
The New Testament was not
yet written
, much less collated at
the time this passage was written in a
letter by Paul,  
to the young pastor, Timothy.
When he became a believer. Paul very clearly and succinctly  
stated his religious beliefs, in Acts 24:14.

"I confess to believing and following The Way that is called a
sect, so serve I the G-d of our fathers, believing all things
which are according to the law, and which are written in the
prophets; having hope toward G-d, which these also
themselves look for, that there shall be a resurrection both of
the just and unjust."
Rightly dividing the
traditions and
interpretations of man  
from the Word of Truth
which is (G-d's Word),
is the instruction here.
Not the division of the
Hebrew Scriptures
[Old Testament]  
and                         
the New Testament!
When Paul met
Y'hshuwah, he did not
disavow Torah or the
prophets, and he
was sent to the
Gentiles,
that they might come to
that same saving
knowledge.