Leila

The first mention of a lamb sacrifice is in Ex 12: The Passover (actually Genesis is the first in the case of Abraham.Isaac) the blood of which was to be placed on the doorposts. On that night the angel of death passed over every household that applied the blood and they were protected. Those that did not - lost their firstborn. Then in Leviticus: We have the various sacrifices for sin and approaching God laid out. Q.1b: How can one person take sin away for the whole world?