How would you define the essentials of the faith, or would you simply leave them undefined.
Are you asking what's essential to saving faith, or what’s essential for the Christian faith to be Christian?
i) Apropos the former: as you know, the Bible states certain doctrines one must believe to be saved.
On the other hand, the Bible also has a principle of graded responsibilities (Lk 12:48; Heb 13:17). So to some extent I expect the propositional content of saving faith is person-variable.
God holds F. F. Bruce to a higher standard than the paperboy.
ii) Apropos the latter: in polemical books that deal with doctrinal controversies (e.g. Galatians, 1 John), the Bible spells out certain fundamental doctrines. So I think it’s possible to draw up a partial list of Christian essentials.
However, those are occasional writings which discuss Christian essentials incidentally rather than systematically. So I think we lack sufficient information to compile a definitive list of Christian essentials.
Ultimately, it’s incumbent on us to believe whatever the Bible teaches. That will automatically include the “essentials” (since the whole includes the part).
iii) Of course, Christian Bible scholars, ethicists, and theologians also spend time trying to distinguish timebound Bible statements from timeless Bible statements. And that’s part of distinguishing essentials from nonessentials. But that exercise is not without various degrees of uncertainty.