While the children of Israel were on the march out of Egypt, God called Moses to come up to Mt Sinai to bring down to God’s people the 10 Commandments that He wanted His people to live by in the Promised Land.
With that law, came instruction on how to build an alter. If the person sinned they were to kill an animal, and pour out its blood over the alter. This was a temporary fix, for the forgiveness for the sin. A law must be enforced, to become a law, so in Ezekiel 18:4 God said: “The soul that sinneth it shall die.” The law had to be enforced, and the breaker of the law, had to be punished. There was no grace, nor love in the Law.
We are told in the New Testament that Jesus Christ said: ” Think not that I am come to destroy the law, or the prophets. I am not come to destroy, but to fulfill. Matthew 5:17
That Law is still in effect today, but because God loved us so much, He gave his only begotten son to die on a cross for our sins. When this happened, grace and love came into the law. When Jesus Christ was crucified on that wooden cross, that old cross, became an alter, and Jesus became the blood sacrifice for our sins.
All we have to do today is ask for forgiveness of our sins, because Jesus Christ paid it all.