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 one evidence of this change from death to life?
What did this bring to him?
With what sins are rebellion and stubbornness classed?
What question did -Christ's wonderful teaching call forth?
How is the true God distinguished from all false gods?
By what is the knowledge of sin?
What proposition did He submit to them?

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