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.

Through whom is this reconciliation made?
Does the Bible recognize what may be called \"present truth\"?
What reason did they give for not receiving Him?
What shows that God imputed sin to Cain?
14. What does the \"psalm for the Sabbath day\" suggest as proper acts and themes for thought and meditation on the Sabbath?
Do Protestant writers acknowledge the same?
How does God anticipate the needs of His children?

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