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.

For whom did Christ suffer all these things?
When God brought His people out of Egypt, how did He republish His law?
How is the law further described?
20. When and by what church council was the observance of the seventh day forbidden, and Sunday observance enjoined ?
When, according to prophecy, were men to amass great wealth?
Do the dead know anything?
What is God's attitude toward the poor?

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