God's 1st covenant with Abraham (Genesis 15) promised to give the land to Christ; it had nothing to do with Israel other than Christ being out of Israel. God's 2nd covenant was circumcision, which obviously wasn't everlasting and found its fulillment and end in the new covenant. But while it was in force it was with Israel alone, and even Christ had to submit to it.
Again, we disagree. It's not unexpected. If you have your basis inaccurate (or wrong), the theology that is built around it will also be inaccurate (or wrong).
The covenant of circumcision is everlasting through Christ. Christ submitted to the Law because He fulfilled the Law, that in Him, we are imputed the righteousness of Christ.
Colossians 2:6 - 15
As ye have therefore received Christ Jesus the Lord, so walk ye in him:
Rooted and built up in him, and stablished in the faith, as ye have been taught, abounding therein with thanksgiving.
Beware lest any man spoil you through philosophy and vain deceit, after the tradition of men, after the rudiments of the world, and not after Christ.
For in him dwelleth all the fulness of the Godhead bodily.
And ye are complete in him, which is the head of all principality and power:
In whom also ye are circumcised with the circumcision made without hands, in putting off the body of the sins of the flesh by the circumcision of Christ:
Buried with him in baptism, wherein also ye are risen with him through the faith of the operation of God, who hath raised him from the dead.
And you, being dead in your sins and the uncircumcision of your flesh, hath he quickened together with him, having forgiven you all trespasses;
Blotting out the handwriting of ordinances that was against us, which was contrary to us, and took it out of the way, nailing it to his cross;
And having spoiled principalities and powers, he made a shew of them openly, triumphing over them in it.