Is cremation against God's will for Christians?
It doesn't matter what is done with us after we move out of our earthly bodies or how our earthly tent is destroyed. We know, that God will raise us from the dead (2 Corinthians 5:1).
Though there are no specific instructions as to how the dead are to be disposed, cremation in Bible is documented as an exceptional method in unusual circumstances.
In 1 Samuel 31:12, the valiant men of Jabesh-Gilead burned the corpses of Saul and his three sons, so that the Philistines couldn't defile their bodies.
Even though we don't find anything mentioned in the New Testament about cremation, the scriptures do not prohibit against it. Though the Church fathers traditionally preferred burial as the right custom it doesn't matter if a Christian gets cremated. What matters is that God will resurrect his body one day (1 Corinthians 15:42-44).
Whether one is buried or is left, to be eaten by animals or birds, the body eventually decays. The Bible tells us in Revelation 20:13 that the sea will give up the dead
within her [even though we know that many underwater species love to eat flesh].
So whether we are buried or we are cremated, we know that one day we will have a resurrected and glorified body that will never die. This is because our God is not the God of the dead, but the God of the living (Mark 12:27).
If cremation in any way, would have effected our resurrection and salvation, we KNOW, that God would have told us.