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.

To whom is our worship justly due?
What promise is made to those who repent and are baptized ?
What question did the disciples then ask?
How should parents bring up their children?
How is the conflict between Christ and Satan described?
How visible is His coming to be?
What special blessings were conferred on the Israelites?

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