The Blood of Abel by Henry Morris, Ph.D.
 

"And to Jesus the mediator of the new covenant, and to the blood of sprinkling, that speaketh better things than that of Abel." (Hebrews 12:24)

There are three references to the blood of Abel in the Bible, with each instance indicating that the shedding of Abel's blood by his brother Cain was a type of the shed blood of Christ. In fact, the very first reference to blood in the Bible (thus, by the "law of first mention," a reference of foundational significance) is God's accusation to Abel's murderer: "The voice of thy brother's blood crieth unto me from the ground" (Genesis 4:10).

Abel was the first of multitudes through the centuries whose blood has been shed because of their witness for divine righteousness (note 1 John 3:12). This indictment of human wickedness reached its zenith in the spilling of the blood of the one who was perfectly righteous. "That upon you may come all the righteous blood shed upon the earth, from the blood of righteous Abel unto the blood of Zacharias" (Matthew 23:35; also Luke 11:50-51).

But if the blood of Abel cries out for vengeance along with "the blood of the saints, and with the blood of the martyrs of Jesus" (Revelation 17:6), the blood of Christ Himself, as our text assures us, speaks of better things than those called forth by Abel's blood. There was an old covenant, demanding blood for blood, with the atoning blood of animals substituting for that of sinners. "And Moses took the blood, and sprinkled it on the people, and said, Behold the blood of the covenant" (Exodus 24:8). But Jesus "is the mediator of the new testament . . . for the redemption of the transgressions that were under the first testament" (Hebrews 9:15), and with His blood, we have "our hearts sprinkled from an evil conscience . . . to serve the living God" (Hebrews 10:22; 9:14). HMM

http://www.icr.org/article/6981/