Christ Earned Our Salvation

The forgiveness of sins does not take place without a payment or satisfaction. You, however, do not make this payment; but it cost Christ His life, body, and blood. Therefore it does you, nay, all the world, no good to sacrifice body and blood; for before God no sacrifice is sufficient to pay for sin (says Scripture) except the one sacrifice of Christ. The fact, then that He has sacrificed Himself for your sin and for the sin of the whole world and gives you His innocence and righteousness -- this comes to your aid and drowns your sin and death.

Source: Quoted in Ewald M. Plass, What Luther Says, A Practical In-home Theology for the Active Christian. St. Louis: Concordia Publishing House. 1959 Edition, 10th Printing (1994), p. 516-517.