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 change is wrought in conversion, or the new birth?
25. When Christ has finished His priestly mediatorial work in the heavenly sanctuary, what decree will go forth?
Is there a specified time for the cleansing of the heavenly sanctuary?
To whom does vengeance belong?
What did Christ nail to His cross?
How often will they congregate to worship the Lord?
When, according to the Bible, does the Sabbath begin?

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