A covenant binds two peoples as one, and it has three parts. First, the two parties must become one by adopting themselves to each other. . We saw this in the Old Covenant with God saying, "You will be my people, and I will become your God."
Secondly, since the greater party cannot give itself up to become like the lesser party, the lesser party must bend. So, in the Old Covenant the lesser party had to adapt itselff to God, by living up to God's Commandments. In the New Covenant we adapt ourselves to union with God by loving each other as Jesus has loved us.
Thirdly, to have one life, the parties must exchange the same blood. In the Old Covenant this happened by the young men sprinkling the blood of steers over the whole assembly, and over God's altar. In the New Covenant Jesus, at the Last Supper offers his own blood as the blood of the New Covenant.