Because the Books of Hebrews, James, First Peter, Second Peter and Jude were written to the Jews, should Gentile believers use the precepts?
As in every book of the Bible, the messianic epistles contain principles that are true universally. For example, the Book of Leviticus, which detailed how the Tabernacle system was to work, was intended only for Israel — specifically, the priesthood. It was intended only for one people (the Jews) and only for a limited period of time (from Moses to Christ). However, there are principles in Leviticus that are universally true. One such principle is that atonement requires the shedding of blood (Leviticus 17:11); this standard always applies. The same thing is true in regard to the various principles found in the messianic epistles, and this is why one must study the context of each verse before deriving any conclusions. The question to be asked is: is the statement or ordinance specifically applicable to one people of a specific period of time, or is it rooted in an eternal principle, one that is always true? Only then can the proper application be made.