Body fluids that leak might contain the virus. That's why it got to be sealed.
Once someone is dead the virus does not get usually transferred. But there are many exceptions - Ebola, hemorrhagic fevers, Cholera etc can get passed on.
The safer option is to cremate, because you are not so sure about the burial due to the water table contamination and other factors.
China made it compulsory cremation. It's faster disposal and a much safer option.
Religious sentiments do not necessarily apply under a pandemic situation.