God requires two things because of our sins....
(1) Death........Rom 6:23 For the wages of sin is death; but the gift of God is eternal life through Jesus Christ our Lord.
Death paid the price for our sins......
(2) Shedding of innocent blood.......Heb 9:22 And almost all things are by the law purged with blood; and without shedding of blood is no remission.
Blood washed away the sins...
This is the requirements for sin that God set down from the foundations of the earth.
However, He also knew that our blood was sinful, and we did not have the power to conquer death, so we could never pay for our sins.
Only God is eternal (thus He could pay for all sins for all mankind for all eternity)
Since God is spirit, He has the power to conquer death (thus giving us the hope of the resurrection)
God is sinless (thus allowing Him to die and pay the price for our sins).
But, before God could do that, He had to be flesh and blood. This is why He came to earth and was born as a human. This allowed Him to (1) die (which He could not do as God)
(2) shed His blood (which He did not have as God)
However, there was a problem. The blood is passed from Father to child (not mother). So, God could not have an earthly Father. Thus, He "spoke" and Mary became pregnant, thus getting around the "father" problem.
Then He died on the cross, spilling every drop of His blood and paying the price for our sins. He then declaired that "all sins" were paid for, and now the only thing anyone will ever go to Hell for is the rejection of God's gift.