Here is evidence that God never truly needed or desired animal sacrifice for the atonement of sin. Animal sacrifice was actually insufficient to cleanse us of our sins. The purpose of animal sacrifice was to remind the one performing the ritual of their own failure and sin. The Son, Jesus, came in a body prepared by his Father, our God, in order to be sacrificed for the atonement of our sins. By that action, those who believe have been sanctified once and for all.