Blood sacrifices have been required by God for several reasons.
After many attempts to convince Pharaoh to let the Israelites go God sent a final plague in Egypt. The plague would kill the first born of Egyptians. To spare the Israelites from this plague He instructed them to put blood on their houses so the plague would pass over them. In Exodus 12:12-13 New American Standard Bible 1995 it says “12 For I will go through the land of Egypt on that night and will strike down all the firstborn in the land of Egypt, both man and beast; and against all the gods of Egypt I will execute judgments—I am the Lord. 13 The blood shall be a sign for you on the houses where you live; and when I see the blood I will pass over you, and no plague will befall you to destroy you when I strike the land of Egypt.”
In this instance the blood was protection for the Israelites from the coming judgement on Egypt.
After the Israelites left Egypt God gave Moses the Ten Commandments and other laws for their instruction and protection.
At that point God required a blood sacrifice for sin. In the Old Testament sheep, goats, and bulls were offered. Exodus 29:14 New American Standard Bible 1995 “14 But the flesh of the bull and its hide and its refuse, you shall burn with fire outside the camp; it is a sin offering.” The Law of Sin Offerings can be found in Leviticus 4. Until Christs death and resurrection God required the blood sacrifice of animals for forgiveness of sin.
Later God provided a better sacrifice for sin. One that will never have to be replaced or sacrificed again. The purpose of Jesus life on earth was die for people’s sin. Jesus while he and the disciples were eating the Passover Feast said Matthew 26:26-29 New American Standard Bible 1995 “26 “Take, eat; this is My body.” 27 And when He had taken a cup and given thanks, He gave it to them, saying, “Drink from it, all of you; 28 for this is My blood of the covenant, which is poured out for many for forgiveness of sins. 29 But I say to you, I will not drink of this fruit of the vine from now on until that day when I drink it new with you in My Father’s kingdom.” At this point Jesus was referring to his death.
The author of Hebrews discusses the two covenants: Hebrews 9:18-28 New American Standard Bible 1995 “18 Therefore even the first covenant was not inaugurated without blood. 19 For when every commandment had been spoken by Moses to all the people according to the Law, he took the blood of the calves and the goats, with water and scarlet wool and hyssop, and sprinkled both the book itself and all the people, 20 saying, “This is the blood of the covenant which God commanded you.” 21 And in the same way he sprinkled both the tabernacle and all the vessels of the ministry with the blood. 22 And according to the Law, one may almost say, all things are cleansed with blood, and without shedding of blood there is no forgiveness.
23 Therefore it was necessary for the copies of the things in the heavens to be cleansed with these, but the heavenly things themselves with better sacrifices than these. 24 For Christ did not enter a holy place made with hands, a mere copy of the true one, but into heaven itself, now to appear in the presence of God for us; 25 nor was it that He would offer Himself often, as the high priest enters the holy place year by year with blood that is not his own. 26 Otherwise, He would have needed to suffer often since the foundation of the world; but now once at the consummation of the ages He has been manifested to put away sin by the sacrifice of Himself. 27 And inasmuch as it is appointed for men to die once and after this comes judgment, 28 so Christ also, having been offered once to bear the sins of many, will appear a second time for salvation without reference to sin, to those who eagerly await Him."
Christ shed his blood on the cross for the remission of sin for all that are willing to accept Him. John 3:16 King James Version “16
For God so loved the world, that he gave his only begotten Son, that whosoever believeth in him should not perish, but have everlasting life.”
God does not want anyone to perish. It is an individual choice to accept or decline the sacrifice. As long as an individual has breath it is never too late to accept the atoning sacrifice Jesus made.
Just as God required the blood on the house for death to pass over the Israelites, so people need the blood of Christ applied to their hearts to escape the second death.