How early was this sacrificial system known?

Answer

"By faith Abel offered unto God a more excellent sacrifice than Cain, by which he obtained witness that he
was righteous, God testifying of his gifts." Heb. 11: 4. See Gen. 4: 3-5; 8: 20.

How great was the agony of His soul?
What shameful treatment did Christ receive from the soldiers?
Is there a limit to the strivings of God's Spirit?
And how may we know that we love the brethren?
What title of distinction is given the law of God?
At His ascension, how did the angels say Christ would come again?
What instruction does the Apostle John give touching this subject?

Questions & Answers are from the book Bible Readings for the Home Circle