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.

Were the gifts of the Spirit to continue forever?
What may be known with equal certainty when these signs have been seen?
What will be the fourth plague?
What is promised those who add grace to grace?
Before he was afflicted, what did he do?
In order to grow by the Word of God, what must one do?
What will be the difference between the portion of the righteous and the wicked?

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