Jesus himself is the example of “alliance” from the Father to the human race:
10. “The law of Moses, the prophets and the psalms” (cf. Lk. 24:27 and 44) was a preparation for the coming of the Son of God upon earth. The Old Testament, comprising the life and culture of the people of Israel, is also the history of salvation.
On coming to the earth the Son of God, “born of a woman, born under the law” (Gal. 4:4), associated himself with social and cultural conditions of the people of the alliance, with whom he lived and prayed. (Ad Gentes 10) In becoming a man he became a member of a people, a country and an epoch “and in a certain way, he thereby united himself to the whole human race.” (Gaudium et Spes 22) For “we are all one in Christ, and the common nature of our humanity takes life in him. It is for this that he was called the ‘new Adam.'”(St. Cyril of Alexandria, In Ioannem, I 14: Patrologia Graeca, 73, 162C.)