It doesn’t make any difference. We’re all turning back to dust; cremation just accelerates the process. It doesn’t confuse God at all—He knows where all the parts are. If we were going to drag these bodies into heaven, we might be in trouble. But God is going to give us brand-new bodies, so it doesn’t make any difference.
Historically, Christians have buried their dead in anticipation of the future resurrection, unlike the pagans who burned their dead. But that’s only tradition; it’s not Scripture.
Also, that was in the days before funeral homes and the exorbitant prices people are charged. I’ve run into instances when people couldn’t afford a funeral and felt guilty about cremation. I don’t think anyone ought to feel guilty about that.
The truth is, it doesn’t matter what you do with your physical body after death because the Bible says this body of flesh is going to turn to dust. It doesn’t matter whether you’re lost at sea, blown up in an airplane, or die of natural causes—your physical body eventually is going to decompose and return to the ground. Cremation only speeds up the process.
Plus, it’s not this present body that we’re going to take to heaven anyway. The Bible says in 1 Corinthians 15:52 that in an instant, God is going to take your old, dilapidated body and change it into your brand-new resurrection body—one that is free from all sadness, free from all sin, and free from all emotional and physical suffering.
So I don’t think Scripture prohibits cremation or donating your body to science. Regarding what to do with a Christian’s physical body after death, I think it’s a matter of what’s best for the family.