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.

By whom were the men directed who thus spoke for God?
To whom is our worship justly due?
Upon what did he rest his hope for forgiveness?
How did persecution affect the preaching of the gospel?
20. When and by what church council was the observance of the seventh day forbidden, and Sunday observance enjoined ?
How is this beast further described?
Why were the ancient Sunday laws demanded?

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