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 is God declared to be?
In reply to his inquiry concerning salvation, what was the Philippian gaoler told to do?
What, then, are the visible proofs of genuine justification by faith?
What did Isaiah say Christ would do with the law?
What definite period is mentioned under this trumpet?
With what were many possessed in Christ's time?
19. Will Satan and his agents attempt to counterfeit the coming of Christ, and work signs and wonders to confirm their pretentious claims?

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