them out through His servant Moses. Then His Covenant was offered to the people of Israel, and was established by blood:

Exod 24:5    And he sent young men of the children of Israel, which offered burnt offerings, and sacrificed peace offerings of oxen unto the LORD.
6    And Moses took half of the blood, and put it in basons; and half of the blood he sprinkled on the altar.
7    And he took the book of the covenant, and read in the audience of the People: and they said, "All that the LORD hath said will we do, and be obedient."
8    And Moses took the blood, and sprinkled it on the People, and said, "Behold the blood of the covenant, which the LORD hath made with you concerning all these words."

     Blood was required for the atonement of the soul. Without it, no reconciliation to God could be made. This act sealed The Old Covenant (Old Testament) among God's chosen people of Israel. And flesh circumcision, i.e. blood 'ordinances' were to be kept as a "token" as long as that Old Covenant was in force:

Lev 17:11  For the life of the flesh is in the blood: and I have given it to you upon the altar to make an atonement for your souls: for it is the blood that maketh an atonement for the soul.

     Even though these events show that there were flesh requirements of receiving and accepting that first Covenant, God was still keeping His first Promise to Abraham by 'faith', which began all the way back in Genesis 15:6.
     What is most important, is that God gave Abraham a Promise before He gave His Law through Moses. And that Promise first given through Abraham was that through him, all the families of the earth would be blessed. Meaning our Lord Jesus Christ would be born of Abraham's seed, and become The Perfect Sacrifice for us; and then the Salvation Promise given to Abraham would be opened up to ALL who would believe on Christ Jesus, as God's Promised Savior.

     Salvation through God's Savior Jesus Christ... is That Promise to Abraham by 'faith', even as our Lord revealed to the Jews in John 8:

John 8:56    Your father Abraham rejoiced to see My day: and he saw it, and was glad."
57    Then said the Jews unto Him, "Thou art not yet fifty years old, and hast Thou seen Abraham?"
58    Jesus said unto them, "Verily, verily, I say unto you, Before Abraham was, I am."

     The "I AM" is one of God's sacred Names. Yes, even Abraham rejoiced in God's Promise of Salvation, that through his seed our Lord Jesus Christ would be born of a virgin, be crucified on the cross for the remission of the sins of many, resurrect to the Right Hand of God, and come to rule all nations (Isa.7:14; Isa.9:6-8; Matthew 1; Matthew 26:26-28; John 19; Psalms 110; Acts 2:29-33; 1 Corinthians 15:22-28) . Our Lord Jesus Christ has always been the Foundation of The Father's Promise first given to Abram:

Gal 3:6   Even as Abraham believed God, and it was accounted to him for righteousness.
7    Know ye therefore that they which are of faith, the same are the children of Abraham.
8    And the Scripture, foreseeing that God would justify the heathen through faith, preached before the gospel unto Abraham, saying, "In thee shall all nations be blessed."
9    So then they which be of faith are blessed with faithful Abraham.

     By the original Promise God first gave to Abraham, Salvation through 'faith', as our 'faith' in God, through His Son, became accounted to 'all' who believe on God's Savior, as the righteousness of Abraham. This is how believers from all families of the earth were to be blessed through Abraham.