Christianity says he is, Paul and the author of Hebrews also.
Read Genesis 15
I am not sure what your point is. The covenant was phased in over time with Abram and then Abraham with G-d repeating the promise after different events. Abram fell asleep to see the exile in Egypt. Deut 31 also predicts exile. But G-d never cancels the covenant and the prohets all prophecy the return of the Jewish people to their and restoration of their relationship to G-d. If G-d would have canceled the covenant, there would be no Jews in Israel today.
Covenants require(d) two parties to be in agreement. A covenant was legally, socially, and morally stronger than any other agreement/contract/arrangement in existence. If two people were in danger--one a close family member and the other a covenant partner--the covenant partner would receive the assistance, and the family member would be left to his/her own devices, even if the danger were mortal.
Covenants were serious things and not to be entered into lightly.
A covenant required that both parties take part in the covenant ceremony so as to be held accountable. The failure to live up to the covenant meant that the life of the person who failed was forfeit. The other party could walk up to him and just kill him on the street with no penalty.
Serious stuff.
God caused Abram to fall asleep. This meant that Abram did not participate in the covenant ceremony. God walked through the animal sacrifices by Himself. He took on the penalties of both parties for any failure by either party.
Man failed. We did not follow Him, nor become His people as He wished. We sinned. Our life is forfeit. That is why He sacrificed His Son. That was Him accepting the responsibility of that covenant.
Jesus' death was a covenantal penalty. We get our eternal life back by believing in Him who took our penalty. So, in a way, I guess you can say it was a sin sacrifice, but not in the traditional Jewish interpretation of that term.
But G-d never cancels the covenant and the prohets all prophecy the return of the Jewish people to their and restoration of their relationship to G-d. If G-d would have canceled the covenant, there would be no Jews in Israel today.
Agreed. The covenant was never canceled. That is why we are still able to come to God by believing on His Son.