In the two readings for today's liturgy, both Jesus and St. Paul speak of the relationship that exists between God and us. That relationship is solidified in a "covenant" or "testament," as in the Old or New Covenant and the Old or New Testament. Throughout salvation history, God has desired to enter into a covenant relationship with the human family, a desire that resulted in several agreements or covenants.
The first of these was the Noahic Covenant which was universal in nature, extending to the entire human race. The second covenant mentioned in the Book of Genesis was the Abrahamic Covenant which included all the descendants of Abraham. Next we read of the Mosaic or Sinai Covenant which cemented the relationship between God and the Israelite people. God also made an Aaronic Covenant establishing the descendants of Aaron as the priestly tribe within Israel. Next we read of the Davidic Covenant which established the Davidic Dynasty and promised that a descendant of David would sit on the throne of Israel forever. Finally, Jeremiah speaks of a New Covenant. We Christians believe that the New Covenant is realized in the person of Jesus Christ. Careful study of the covenant relationships that develop throughout the Hebrew Scriptures leads us to the conclusion that God created us to be in a close, mutual and personal relationship. In other words, God created us to love and serve God on this earth and to live with God forever in the next life.
St. Paul tells us today that we can place our confidence in this relationship because of Jesus who has sealed that covenant relationship by his blood. For the Hebrew people, blood was life. By shedding his blood, Jesus has sealed an unbreakable covenant between God and us.
As we continue to read from the so-called Sermon on the Mount in the opening chapters of St. Matthew's Gospel, Jesus assures us that he did not come to destroy the covenant (the law), but to fulfill it. That fulfillment came with a price, his own life, his blood.
Pope Pius XII referred to us as spiritual Semites. By that, he meant that our relationship with God through Jesus comes through the history of the Hebrew people. God's self-revelation culminating in the person of Jesus can only be understood through the history of the Chosen People. Do not think that I have come to abolish the law or the prophets. I have come not to abolish but to fulfill. (Matthew 5:17)