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 the foundation of faith?
And what besides a mere belief in the truth is necessary?
From what time was Christ, the Word, associated with God, the Father?
How long was Jerusalem to be trodden down of the Gentiles?
On opening the fifth seal, what was seen under the altar?
Why does Christ desire this growth in His followers?
How willing is God to hear and answer prayer?

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