The study indicates the extreme importance of FAITH. Adam, Noah, Abraham , Moses, The Prophets, Yochanan ben Zechariah, Peter, Paul, et al, had much FAITH. It makes no difference if you're referring to "Old Testament" times or "New". Besides which, there is no old or new; it's all the same.
Even with the differences in Priesthood, Melchizedek vs. Aaronic, and the temporary suspension of certain aspects of the Priesthood as it relates to Torah, FAITH is still required.
Concerning our one and only High Priest and one and only Rabbi, Yeshua, we fully accept His propitiation for us; His free gift.
We are hopefully called, then, by the FATHER, through Yeshua, which is the only way to reach the FATHER at this point in priestly history. (one could argue it's always been this way - Yeshua's fingerprints are all over the Tanakh)
As further indicated in the study, this FAITH stirs us to have Love and Respect for the FATHER, which leads us to the totality of Obedience to Him and the "refining works" of His Torah (as much as we can).
We know this obedience to Torah does not infer Salvation and never has. Salvation comes purely through FAITH.
The act of circumcision and practicing observances laid out in Torah makes us a member of the Commonwealth of Israel. To repeat, we do this out of love, not for Salvation.
Now ... here's the rub ...
All of this mentioned above does not necessarily make us one of the Chosen, or a Saint, or a member of the Elect! (Chosen, Saint, Elect are synonyms)
... for, "many are called, but few are chosen". (Matt. 22)
We know that our love and obedience to Him must be with a circumcised heart of flesh, not an uncircumcised heart of stone.
Who is the JUDGE then? Who decides if we have been chosen? Yeshua does ! Thankfully, it is not for us to judge. Heaven knows, we have to make judgments enough in our daily lives.
But here is the point in all this. What about the ones who never have the above understanding? What about the Christians that go to church every Wednesday night and twice on Sunday who have never been called by the FATHER and does not even recognize the validity of Torah? What about those who celebrate the pagan feast days and ignore the appointed times (moedim)? What about the Jewish brothers and sisters who diligently follow Talmud and all the instructions given to them by their human Rabbi? It may surprise you but most Jews do not follow Torah, they follow man's instruction instead! Most Jewish folk believe that Salvation comes from following man's "fence of instruction" surrounding Torah. Even Karaite Jews, who famously proclaim they follow Torah instead of man, believe that Salvation comes from following Torah. It does not! It comes from FAITH. (their are exceptions in all groups, of course)
The road to destruction is broad indeed, and the narrow gate and path is very narrow. No wonder we should work out our Salvation with great FEAR and TREMBLING!