Why did Jesus have to die to save us?

For reasons we don't fully understand, God has a "blood" economy. It is written in our humanity. Even ancient non-Christian religious rites often included blood sacrifices, both animal and human.  

A bit of definition here:

Covenant: A will or agreement.

Old Testament = Old Covenant. It was defined by Jewish Laws whereby sinners were made right with God, primarily by obedience and animal blood sacrifices.

New Testament = New Covenant. Defined as God’s new and “revised” agreement or will that replaces the old covenant.

----------------------------------------------------------------------------------------------------------------

Jewish Law (prior to Christ) states that “without the shedding of blood, there is no remission of sin.” (Hebrews 9:22)  According that Law, once a year on the Day of Atonement – animals were sacrificed in order to receive a kind of progressive forgiveness for sins. Then, every year, they would have to repeat it again.

When Jesus (the promised Messiah) was born, the New Covenant was being ushered in – but not here yet! The New Covenant of forgiveness through faith alone (Grace!) did not fully replace the Old Covenant Law until after His death.

A Death Was Required.

It states in Hebrews 9:16-17 (NIV) “In the case of a will (covenant), it is necessary to prove the death of the one who made it, ¹⁷ because a will is in force only when somebody has died; it never takes effect while the one who made it is living.” And Hebrews 9:18 says “¹⁸ This is why even the first covenant (Old Testament Law) was not put into effect without blood.

In Summary:

Traditionally (in the Old Testament), an act of sacrifice began with the sinner transferring their identity to the animal through an act of consecration. Afterward, the animal was killed so that the person was reincorporated into the people of God.

The Apostle Paul describes the New Covenant as a process that begins with Christ identifying with us. He took on our sin on the cross and died as the only perfect and acceptable sacrifice -- and it ends with the consecration -- us identifying with that which was sacrificed. In other words, once the ultimate perfect sacrifice was made (Jesus’s death), there was no further need for any future sacrifices to be made – ever! God’s justice was satisfied.

In a sense Paul sees, in Christ, God coming to put an end to sacrifice by turning it upside down.  God (in Christ) came to sinners -- instead of sinners approaching God through sacrifice -- providing His forgiveness through the only perfect acceptable sacrifice of His only Son, Jesus Christ.

The only requirement for receiving God’s forgiveness through Jesus is that we accept it with a heartfelt “What an Awesome God!” and “THANK YOU.”