Universal Laws according to the Bible:
All who sin must die.
For the wages of sin is death... (Romans 6:23)
Sin can be washed only by an innocent blood
In fact, the law requires that nearly everything be cleansed with
blood, and without the shedding of blood there is no forgiveness.
(Hebrews 9:22)
The blood of animal cannot take away sins.
It is impossible for the blood of bulls and goats to take away sins.
(Hebrews 10:4)
Universal Truths according to Bible:
All are sinners.
for all have sinned and fall short of the glory of God (Romans 3:23)
All must go to Hell.
Death in Biblical context refers to Spiritual Death, which is
separation from God or living in Hell. Therefore, since all are
sinners, all must die and all must go to Hell.
God gave His one and only Son to die for us:
For God so loved the world that he gave his one and only Son, that
whoever believes in him shall not perish but have eternal life. (John 3:16)
Jesus Christ sacrificed his blood: Since all humans are sinners and animal blood cannot take away sins permanently, only the the blood of the Jesus Christ the sinless one can take away our sins. Jesus sacrificed himself for us by dying on the cross, by pouring out all his blood and taking all our punishments on him.
God made him who had no sin to be sin for us, so that in him we
might become the righteousness of God. (2 Corinthians 5:21)
Anyone who believes Jesus Christ will not be condemned:
Therefore, there is now no condemnation for those who are in Christ
Jesus, because through Christ Jesus the law of the Spirit who gives
life has set you free from the law of sin and death. For what the
law was powerless to do because it was weakened by the flesh, God
did by sending his own Son in the likeness of sinful flesh to be a sin
offering (Romans 8:1-3)
Philosophical explanation of how the whole thing works (source):
We can no more defy this law and live than we can defy the law of
gravity by jumping out of an airplane without a parachute. The end
result will be death unless—unless we apply another law, the law of
aerodynamics. This law makes it possible for an airplane to fly and a
parachute to lower us to the earth gradually and thereby save us.
There is another universal law that we cannot defy and live. It is
"the law of sin and death," which means that the judgment and penalty
of all sin is death and eternal separation from God. That is, unless
we apply a higher law which is "the law of the Spirit of Life," which
is a God-given "spiritual parachute" to save us from eternal death.
God provided this law through the death of Jesus who died in our place
to pay the penalty for our sin.
Furthermore, because God is also a God of absolute holiness, no sin or
unforgiven sinners can survive in his presence. As some bacteria are
not able to survive in the light and die if they are exposed to it, so
it is with us. In our sinful state if we were exposed to God and his
incredible light, we would be destroyed instantaneously. And herein
lies our dilemma.
However, God's answer to our dilemma lies in the fact that God is not
only a God of infinite justice and absolute holiness, but also a God
of eternal love. Because of his love, God gave his very own Son, the
Lord Jesus Christ, to die on the cross in our place to pay the penalty
for our sins to meet the automatic demands of his (God's) justice and
holiness. Christ's death made possible God's "law of the Spirit of
Life"—our God-given "spiritual parachute"—to save us from eternal
death.
(All verses in New International Version)