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.

With whom did sin originate?
What was the Comforter to do when He came?
What provision has been made so that we may keep God's law?
What similar charge was brought against the Apostle Paul?
What are all admonished to do when these signs have appeared?
What warning has Christ given that we might not be taken by surprise by this great event?
14. What scripture for ever precludes the idea that the dead come back to earth to communicate with the living?

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