We all like to have friends. Close friends usually have a lot of things in common which they can do together or talk about together. As children we may have promised that someone was our 'special' friend forever. Sometimes friends even pricked their fingers and mixed their blood to be "blood brothers/sisters."
The Bible tells us that God becomes the special friend of all the people who trust him and who follow the Lord Jesus Christ. The Bible uses a special word to describe this friendship: it is called a covenant. It is not the ordinary word that people use for a covenant (like the agreement of two people when they get married — though this is also a covenant). The word used in the Biblefor the friendship of God and his people is special, because it is God himself who makes the covenant and gives his promise that he will always keep to what the covenant says.
God promises in the covenant with his people that when they become his friends he will never never let them down or go back on what he has pledged himself to do. So when Jesus said "This is my blood of the covenant", it means that those who follow him and his ways are saved and saved forever. God never breaks his promises. That is a great comfort and encouragement for us to continue as 'special friends' with God — living happily with him.
Dear Lord, I do thank you for your covenant of special friendship with me through the Lord Jesus. Amen.