Through the angel the Father's named His Son, Jesus. This indicates that Jesus' primary obedience is to His heavenly Father and not to Joseph. By Jesus' perfect obedience we have a perfect righteousness, justification and eternal life.
We trust that for the sake of His obedience alone we have the forgiveness of sins by grace, are regarded as godly and righteous by God the Father, and are eternally saved. It is the same thing when Paul says "by the one man's obedience the many will be made righteous" (Rom. 5:19) or "so one act of righteousness leads to justification and life for all men" (Rom. 5:18). Faith justifies because it lays hold of and accepts Christ's merit in the promise of the Holy Gospel. For this merit must become ours through faith. Therefore, the righteousness that is credited to faith or to the believer out of pure grace is Christ's obedience, suffering, and resurrection, since He has made satisfaction for us to the Law and paid for our sins. Christ is not man alone, but God and man in one undivided person. Therefore, He was hardly subject to the Law (because He is the Lord of the Law), just as He didn't have to suffer and die for His own sake. For this reason, then, His obedience (not only in His suffering and dying, but also because He was voluntarily made under the Law in our place and fulfilled the Law by this obedience) is credited to us for righteousness. Because of this complete obedience, which He rendered to His heavenly Father for us by doing and suffering and in living and dying, God forgives our sins. He regards us as godly and righteous, and He eternally saves us. (paragraphs 11-15)
Condensed from CONCORDIA: THE LUTHERAN CONFESSIONS, copyright 2005,2006 by Concordia Publishing House. Used by permission. All rights reserved. To purchase a copy of CONCORDIA, call 800-325-3040.