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 many are sinners?
How did the father show his joy at his son's return?
What is the ground of justification on God's part?
What instruction is given in the New Testament regarding marriage with unbelievers?
What does God say the Sabbath will be to those who hallow it, or keep it holy?
19. Will Satan and his agents attempt to counterfeit the coming of Christ, and work signs and wonders to confirm their pretentious claims?
What encouragement is held out concerning the branches which have been broken off?

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