Hebrews 9:13-14
For if the sprinkling of defiled persons with the blood of goats and bulls and with the ashes of a heifer sanctifies for the purification of the flesh, how much more will the blood of Christ, who through the eternal Spirit offered himself without blemish to God, purify our conscience from dead works to serve the living God.

The Bible is clear that the sacrifice of Christ is the only sacrifice that can provide forgiveness of sins, so that even the animal sacrifices made in the Old Testament were dependant on Christ’s then future sacrifice. Abraham, Moses, David, and all of the other Old Testament people were forgiven only on the basis of Jesus Christ’s sacrifice. They trusted that God would forgive them because of the Messiah He had promised to one day send.

God did not forgive them on the basis of their faith or their faithful practice of the sacrifices, but because of what Christ would one day do. Their faith looked forward.

Our faith, on the other hand, looks back on what Christ has already done. We are justified solely by His blood, and that is a free gift of God’s grace, not based on our own merit. [Romans 6:21-23; Ephesians 2:6-10]

Regardless of what century a person lives in, people have always forgiven on the basis of Christ’s atonement, and on that basis alone. The difference in the New Testament is that the person and work of Christ have been revealed, instead of hinted at as in the former covenant. This is why the Old Testament sacrifices are referred to as shadows or symbols of Christ – they pointed to the greater reality that would be fulfilled in and through Christ.

And what does this forgives through Christ produce? A spirit of service. We who have been purchased by the blood of Christ are now His ambassadors, charged with taking the message of reconciliation to a world lost in darkness. “Salvation is in no one else, for there is no other name under heaven given among men by which we must be saved.” [Acts 4:12]