"For the life of the flesh is in the blood…" Lev 17:11 (NKJV)
Blood is the life-maintaining fluid that circulates throughout not only the human body but also that of animals, reptiles, birds, fish and insects. Medical science tells us that the human body has approximately seven to twelve pints - which is approximately five to ten liters  -  of blood circulating through it at any given time. That's equivalent to seven percent of our human body weight. Blood carries; nourishment, electrolytes, hormones, vitamins, antibodies, heat and oxygen to, and waste matter and carbon dioxide away from the body. Blood is crucial for the survival and sustenance of every human being. If the blood were drained from our bodies, we would die. Similarly, if Jesus Christ did not shed His blood for us, we would wither and die spiritually. Jesus said; "I Am the vine, you are the branches. He who abides in Me, and I in him, bears much fruit; for without Me you can do nothing. If anyone does not abide in Me, he is cast out as a branch and is withered…" (Jn 15:5 NKJV). Jesus said that without Him we can do nothing and "if anyone does not abide in Me, he is cast out as a branch and is withered." What happens to a branch when it is cut off from a tree? It dies. In like manner without the blood of Jesus Christ no one can be saved. It is only for the fact that Jesus shed His blood that we are able to abide in Him and He in us. It is because of His shed blood that we have been forgiven and cleansed of our sins making it possible for us to be reconciled to God the Father in Him and receive His Holy Spirit by whom He abides in us and we in Him. That is one of the reasons why so many people, families and churches are failing and not seeing victory, because the blood of Jesus Christ has been rejected or ignored, even by some Christians, to the point where we are not hearing enough about it in the Church. A bloodless Gospel is a powerless Gospel. Take the blood of Jesus Christ out of the Gospel and you have a powerless Gospel which in turn will produce a dead, dry Church with a dead, dry congregation devoid of any gratitude for what God has done for us in and through His Son. A life without the blood of Jesus Christ is a life devoid of the Holy Spirit and a life devoid of the Holy Spirit is a life devoid of salvation, redemption, justification, sanctification, abundance of life and eternal life. A life that is spiritually dead.
"The thief does not come except to steal, and to kill, and to destroy. I have come that they may have life, and that they may have it more abundantly. "I am the good shepherd. The good shepherd gives His life for the sheep" (Jn 10:10, 11 NKJV). Jesus Christ declared that He came so that we may have life and have it more abundantly. The word "abundantly" in the Greek here literally means; "more superabundant" or "super abundance." Not just enough but more than enough. The illustration we are given here in the Greek is of a cup that is  filled until it overflows onto its saucer so that you are no longer drinking out of the cup but also out of the saucer (Ps 23, all. Esp vs. 1 and 5), so too Jesus came so that we may have this type of abundance in our spiritual and natural lives. We serve a "more than enough" God. How did Jesus make it possible for us to have this "abundance" of life? By suffering, shedding His blood, dying and rising from the dead. Here an exchange was made from the spiritual and natural death we inherited from the original sin of Adam and Eve and experience as a result of our own sins, to the abundance of spiritual and natural life in this life as well as eternal life we have inherited from being in a relationship with Jesus Christ. Our death for His life as a result of His life, death and resurrection. Just as blood carries life to every part of our bodies, so too the blood of Jesus Christ has made it possible for us to have abundance of spiritual and natural life as well as eternal life. And just as blood carries impurities (waste matter) out of our bodies, so too the blood of Jesus Christ has achieved forgiveness, cleanses us from all sin (1 Jn 1:7-9) and removes the power of sin, Satan, demons, the flesh and the corruption of the world from our lives.
Covenant Blood
"Likewise He also took the cup after supper, saying, "This cup is the new covenant in My blood, which is shed for you" (Lk 22:20 NKJV)
In ancient (Old Testament) times, relationships were established upon and maintained through covenants. Covenants were the means by which people, especially strangers - that is, those who were not related biologically - could relate to each other and God to (His) people. Existing mainly so that strangers could have the means by which to relate to each other, if a relationship were to exist and prosper, it had to be through a covenant that was made between the two parties involved. Covenants were extremely important as they provided the means by, foundation upon and atmosphere in which a relationship could survive and thrive. Just as a house cannot stand unless it has been built upon a strong foundation, established upon rock and certain plants or animals cannot survive unless under certain climates, so too covenants provided the foundation upon or climate within which certain relationships could survive and prosper.
Covenants are also important in that certain things are lawful within a covenant relationship that would not otherwise be lawful and actually considered sinful in any other context. For example; sexual intimacy was created by God to be enjoyed by a man and his wife, joined in the covenant of marriage, as a benefit of the marriage covenant. In this context, sexual intimacy is sacred, joining the husband and his wife in the bond of love, strengthening the relationship as well as being the means by which life is created but outside the boundaries of a marriage covenant destroys families, relationships and lives. Why? Because sexual intimacy was created for the marriage covenant to help strengthen it but when taken out of its proper context is destructive as it is now being abused - it is no longer being used the way God intended. Just as a knife that is made for cutting and preparing food becomes a tool of destruction in the hands of a murderer to take life instead of sustain it and becomes such because it is being abused - it is no longer being used in the way originally intended - so too sexual intimacy outside the marriage covenant becomes destructive.  This is the very reason why so many marriages are falling apart, because we do not understand the marriage covenant or covenant for that matter. We in the twenty first century have become ignorant to what covenant is and means. We do not understand what it means to be in a covenant relationship with God therefore we have difficulty relating to God and in turn relating to each other. If we had a better understanding of covenant not only would our relationship with God be stronger but we would have less marriage and relationship breakdowns.
What is a covenant? The word Covenant is an ancient word originating from the Old Testament. It is here that the word first appears indicating that covenant is a heavenly concept, God's idea, initiated by God as a means through which God can relate to man, man to God and man to each other. The title "Old/New Testament" is really "Old/New Covenant", the word "Testament" was used to replace the word "Covenant" by the translators of the King James Version of the bible to help clarify its meaning. Although "Testament" is not inaccurate "Covenant" is the word used in the original text and is a stronger rendition of the idea that is being presented in the Hebrew and Greek Scriptures. The word "Covenant" in the Hebrew literally means: an agreement or relationship established upon the cutting of flesh and shedding of blood. The word that is used in the Hebrew is beriyth which means: in the sense of cutting. A compact (because made by passing between pieces of flesh):- covenant, league, confederacy, confederate (alliance) (1285. Heb. The New Strong's Expanded Exhaustive Concordance of the Bible). In the Greek the word used is diatheke which means: a disposition, a contract, (a divisory will); - covenant, testament (1242. Greek. The New Strong's Expanded Exhaustive Concordance of the Bible).
In Old Covenant times, covenants were practiced by all people whether Hebrew or Gentile. It was customary, no matter what nation or culture you belonged to that if two people, families, tribes or nations desired to create an alliance, that a covenant was established between the two parties. The issue of interest here is not how covenants were made between pagan nations but how God made covenants with His people and how God's people made covenants with each other. It is in understanding this that we will catch a glimpse into who Jesus is, why He did what He did and said what He said throughout His ministry and particularly at the last supper.
The Bible is a book of covenants. We see throughout the scriptures, especially the Old Testament, that God initiated covenants with His people in order to establish relationships with them. This is the driving force behind why God established covenants with His people: a desire for relationship with us. Why does He want to have a relationship with us? Because of His love towards us. Jesus Christ is the sacrifice of the New Covenant who shed His blood for the salvation of all mankind. John the Baptist called Him "The Lamb of God who takes away the sins of the world!"(Jn 1:29 NKJV). Paul the Apostle wrote; "For indeed Christ, our Passover, was sacrificed for us." (1 Cor 5:7 NKJV). Why did God send His Son into the world? Because of His love towards us. "For God so loved the world that He gave His only begotten Son, that whoever believes in Him should not perish but have everlasting life." (Jn 3:16 NKJV). It is through covenant that we can walk in a personal relationship with God, know Him intimately and receive everything He has for us. This covenant has been sealed by, ratified or activated in the shed blood of Christ and it is through this that we have access to God, His throne and the riches of His kingdom as sons and daughters of the Most High.
"Therefore brethren, having boldness to enter the Holiest by the blood of Jesus, by a new and living way which He consecrated for us, through the veil, that is, His flesh, and having a high priest over the house of God, let us draw near with a true heart in full assurance of faith, having our hearts sprinkled from an evil conscience and our bodies washed with pure water. Let us hold fast the confession of our hope without wavering, for He who promised is faithful" (Heb 10:19 23 NKJV).