We might wish to consider these words from Concordia: The Book of Concord:
“Regarding the adversaries’ quoting the Fathers about the offering for the dead, we know that the ancients speak of prayer for the dead, which we do not ban.” (Ap. XXI:94)
and
“Epiphanius declares that Aerius maintained prayers for the dead are useless. He finds fault with this. We do not favor Aerius either.” (Ap XXI:96).
While Lutherans clearly rejected the notion of Purgatory and the idea that our works or services here (including the Mass as Rome conceives it) could actually relieve the sufferings of the saints in purgation, they did not hesitate to offer prayers for the dead that are in accordance with the Word of God. So we have in Starck's Prayer Book the following prayer offered in the presence of the deceased:
O holy and righteous God, it has pleased You to call from this life the departed lying here before us by temporal death. Let us learn from this death that we, too, must die and leave this world, in order that we may prepare for it in time by repentance, a living faith, and avoiding the sins and vanities of the world. Refresh the soul that has now departed with heavenly consolation and joy, and fulfill for it all the gracious promises which in Your holy Word You have made to those who believe in You. Grant to the body a soft and quiet rest in the earth till the Last Day, when You will reunite body and soul and lead them into glory, so that the entire person who served You here may be filled with heavenly joy there. Comfort all who are in grief over this death, and be and remain to the bereaved their Father, Provider, Guardian, Helper, and Support. Do not forsake them, and do not withdraw Your hand from them, but let them abundantly experience Your goodness, grace, love, and help, until You will grant them also a happy and blessed end. Hear us for Your mercy’s sake. Amen. (Starck’s Prayer Book Revised Concordia Edition, p. 345)
If anyone asks what is the use of such prayers, consider “God certainly gives daily bread to everyone without our prayers...but we pray in this petition that God would lead us to realize this and receive our daily bread with thanksgiving.” Similarly, God gives eternal life to all His people, even without our prayers, but when we pray for the blessed dead, we ask God to give precisely what He has promised so that we would realize this and receive His promise of eternal life with thanksgiving, and be comforted by His resurrection Gospel.