As Hosea 6:6 and Matthew 9:13 affirm, God desires mercy and not sacrifice, yet He also affirms that without the shedding of blood there is no remission of sin. The task of the Bible student is not to pitch one verse against another, but to reconcile them.How could the true God -- not a pagan god -- do what the OT prophets say He did not desire and what Jesus affirmed He did not desire?
The question is how God can be 'Just and the justifier of the one who has faith in Jesus' (Rom. 3:26). How can a righteous God, a righteous Judge, who is 'angry with sinners every day' (Psalm 7:11), forgive sin? His justice demands that it be punished; His mercy pleads that it should be forgiven.
It is done by Penal Substitution.
On the cross, all the sins of God's elect were heaped upon the sinless shoulders of our Lord, and His perfect righteousness credited to those who believe. Christ has borne our sins once and for all, so that now God's wrath is propitiated and He can show mercy without requiring a sacrifice, for the blood of the Saviour has been shed once and for all, thereby fulfilling Hosea 6:6, Matt. 9:13 and Heb. 9:22.
Wonderful! Penal Substitution is just the greatest doctrine of all! No hope without it.