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There should be a vast difference between a Christian funeral and that of a non-believer. It is the difference between light and darkness, joy and sorrow, hope and despair, heaven and hell. A Christian funeral should, first and foremost, reflect the words of the Apostle Paul: "Brothers, we do not want you to be ignorant about those who fall asleep, or to grieve like the rest of men, who have no hope" (1 Thessalonians 4:13). Paul uses the euphemism "fall asleep" to refer to those who have died in Christ. The grief of the relatives of an unsaved person is not to be compared with that of those whose loved one died knowing Jesus Christ as Lord and Savior. We grieve in a completely different way because we know we will see them again. The unsaved have no such hope, so their despair is complete and unrelenting.
Perhaps no other event in life brings us as close to the reality of eternity as death. One moment our loved one is here-breathing, communicating, heart beating-and the next moment he is gone. Even though the body remains, anyone who has been present at the moment of death knows that body is empty and the person who once inhabited it has left. If the deceased was a Christian, it is the knowledge of his destination that gives us the hope that unbelievers simply cannot experience. That hope should be the focus of a Christian funeral. The message of that hope should be clearly proclaimed, whether by formal preaching of the gospel of Christ or by memorials by those who knew the deceased and can testify that he/she lived in the light of the hope of eternal life available in Christ. If music is to be part of the funeral, it too should reflect the joy and hope being experienced at that very moment by the departed soul.
Above all, a Christian funeral should provide a glimpse into that brighter world, a world where all Christians will be reunited, where the bonds of love shall be made stronger than they were here, never again to be severed. It is only this hope that can soothe the pains of grief at parting. It is only when we can look forward to a better world, knowing we will see our loved ones again, love them again, and enjoy worshipping God with them forever that our tears are made dry. A Christian funeral should be a celebration of the joy of these glorious truths.
See http://www.gotquestions.org/Christian-funeral.html