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.

What record answers to this prophecy?
Why does God manifest such mercy and long-suffering toward men?
What, therefore, did God say He would make?
What was offered in this sanctuary?
Under what figure was the Christian church represented to the Apostle John?
What is the purpose of the Federal Council of the Churches of Christ in America?
How are the people described who are developed by the threefold message here referred to?

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