I get this question often.
First, it’s important for Christians to keep in mind that this is a question the first Christians- or Jews for that matter- would’ve also asked.
Second, it’s important for Christians to realize the first Christians- and Jews- were well aware (perhaps much more so than contemporary people who can push death off into hospital wards and nursing homes) of what happens to material bodies when they die.
Third, it’s important for Christians- and Jews- to remember that Resurrection flew in the face of what every worldview and religion in the ancient world presumed.
And yet, Resurrection was the fundamental Christian proclamation.
Now, to the question.
There’s a story, which may be just a story, of a pagan asking an early Church Father (Origen, I think): ‘What if a Christian is eaten by a cannibal? In the resurrection, whose body would be raised? The eaten or the eator?’ It’s best not to think too hard or impose our categories of what’s possible on resurrection was the reply.
And that’s usually how I respond. It’s certainly not good news that if someone’s body is lost or ruined then they can’t participate in the resurrection. Just as its best not to think too woodenly about the continuity of my earthly body and my resurrected body. The stress is on the material nature of eternal life; scripture isn’t implying that if you’re bald now you will be eternally.
And I’m an organ donor myself.
But here’s my BUT.
I don’t like cremation. Not because I think the God who made heaven and earth and raised Jesus from the dead can’t somehow restore a cremated person to full resurrected life in the new creation.
I don’t like cremation for aesthetic reasons. In the same way, I don’t like it when communion is served with eenie weenie pieces of bread and little plastic individual cups. It’s supposed to be a feast. The liturgy uses feast language because that’s what God’s Kingdom is like. Eenie weenie pieces of bread point to something else.
I don’t like cremation because the language of our faith (and the funeral liturgy) points to bodily resurrection, and the popularity of cremation goes hand in hand I suspect with modern Western Christians no longer making resurrection the central claim of their faith.
We in the West forget that cremation is still very much forbidden and/or looked down upon among Orthodox Christians, Jews and African American Christians- groups that haven’t lost the importance of incarnation and the body in scripture.