Offerings to God in the Old Testament

Question

One more example would be the almost 15 chapters in Leviticus where they talk about sin offering, burnt offering, grain offering, etc. Why?

Answer

Leviticus was predominantly a handbook for the ancient priests and Levites, providing them with instructions regarding worship. One important aspect of this worship was the sacrifices or offerings that God demanded of the people. They were designed to show praise and thankfulness to God, but also to atone for the Israelites’ sins, by covering and removing the sin, and therefore to obtain forgiveness, because even the Israelites knew that we cannot forgive ourselves. To save the life of a sinful person and ensure that they would not be destroyed by an angry God, an animal was sacrificed, on the understanding that the animal’s life would be a substitute for the person’s life.

With Jesus’ death on the cross, such offerings and sacrifices obviously no longer became necessary, since Christ sacrificed Himself once and for all for all our sins, forever.