Asslamu Alikum:

My wife asked that question because I am trying to justify that cremation is not allowed either in an old testimon, or not even in Islam. She said that if god not allowed us to take any part from our body as the whole body is a loan god give it to us and he wants the whole body back the way he give us. She argued that because we are not allowed to cremate the body than why we do surgery like kidney removal or other operations to take body parts out?
My wife asked that question because I am trying to justify that cremation is not allowed either in an old testimon, or not even in Islam. She said that if god not allowed us to take any part from our body as the whole body is a loan god give it to us and he wants the whole body back the way he give us. She argued that because we are not allowed to cremate the body than why we do surgery like kidney removal or other operations to take body parts out?

There are no Old Testament or New Testament prohibitions against cremation. Christians believe God will have no problem putting us back together, even if we were eaten by a lion or sea creatures, blown apart in an explosion, burned to ashes in a fire, or disintegrated into dust in a grave.

There is nothing that specifically addresses cremation in the Bible. However, there is nothing that addresses driving a car either. The Catholic church used to forbid it, however, in our church, Catholic, more than 1/2 of the funeral services today are with cremains. My mothers service and in the future mine and my wife will be with cremains. Some people won't accept it others do. The local Catholic monastery, Holy Spirit, Conyers, GA, offers direct in ground burial, no embalming or casket. Here is a section of their website-NATURAL CEMETERIES AND GREEN BURIALNatural cemeteries save land and create significant nature preserves. Natural or “green” burial is simple and affordable. A plain pine box or shroud is used in a return to traditional practices. Cremated remains are also accepted.
Think of all the people who were killed in the Twin Towers, very few "bodies" were ever found. God accepted them, He didn't say, "Sorry, not enough parts"! If you want to try and rationalize things, all bodies decay and are not whole. Will you look like a 90 year old person with wrinkles and saggy arms or maybe 1 day old baby? Who knows?