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.

In what other way is God's love sometimes shown?
To what does the blood of Christ witness?
What great truth was then stated?
What did this little horn do to the people of God?
What did Christ say would be the moral condition of the world just preceding His advent?
24. What psalms seem to have been written especially for the comfort and encouragement of God's people during the time of the seven last plagues?
What is the gospel to everyone that believes?

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