Background and historical context The Apostle Paul warned the Church at Philippi:  they should all understand their claim to salvation, …work out your own salvation with fear and trembling,  Philippians 2:12b This book is to help Christians understand God’s plan for salvation. We carefully examine the letter to the Hebrews, verse by verse. For those who question our faith, we should have a ready answer. We can’t explain it to others until we fully understand it ourselves. First some background information that help us understand Hebrews. 
As is true of human institutions, over time they change and become much different from what they were in the beginning. The Jewish Temple also changed. For example, from the first High Priest until the Babylonian exile the office was a lifetime appointment. The spiritual aspect of seeking God was paramount, but ritual was still observed. Between the Babylonian exile until the Roman destruction of the Temple in 70 AD, High Priest’s office became highly political and, eventually, an appointment by Gentile Roman authorities. The spiritual effectiveness of the Temple became an afterthought by Jesus’ day. Few people were seeking a personal relationship with God, as He intended.  The Sadducees, who came to power, didn’t even believe in an afterlife, spirits, or angels. Ritualism and empty tradition failed to inspire the nation to seek God. Graft had penetrated Temple administration. John the Baptist and Jesus began to turn the people's hearts towards God, and were killed for challenging the Temple status quo.  Jewish leadership engineered Jesus' trial and death. After Jesus was resurrected from the dead, the Holy Spirit began to perform various Temple miracles to force the priesthood to accept Jesus as Messiah. They resisted God, and in 70 AD, the Romans broke through the northern wall of Jerusalem after a five-month siege and utterly destroyed the Second Temple.  
Sacrifices for sin stopped, without any Scriptural foundation, the Jewish leadership substituted repentance and charity for redemption from sin. The Jewish nation has not offered a blood sacrifice for their sins for 2000 years. Most Jews have ignored the long-awaited Messiah to this day. In the last chapter, I discuss various interesting miracles God performed, teaching the Levitical priesthood is over. Had Hebrews been written after the destruction of the Temple, the author would likely have argued these miracles documented in the Jerusalem and Babylonian Talmud offer further proof the Old Covenant is over.