Beautiful question. You can give her some examples of material things that cannot be killed or destroyed by knife, for example water, air, fire, space. Energy also cannot be destroyed. So too thoughts and feelings and will cannot be destroyed by any external force. This way she will understand that there are many things even within the range of our human experience that cannot but cut or destroyed by knife or burnt because the substance of which they are constituted is different. Even there are physical bodies, of hydra for example, that cannot be destroyed by cutting. It grows again. In other words there are so many different types of creation in this universe that cannot be destroyed. In fact the atoms that constitute solid body also cannot be cut or destroyed. This way her mind will grow wider and become ready to receive deeper things. Then you can explain that so too the Soul is made up of elements of which the fire and electricity are made. One cannot destroy it by knife or burn it. When the body is burnt after death, the soul emerges safe and being of a similar nature as light it travels in a body of light further on.
This body of light is normally not visible because our eyes are tuned to certain frequencies only. They cannot see or hear out of that range. The soul is seen and can be heard only if by persistent meditation our mind can get tuned to the frequency of the soul and hence see as well as hear its vibrations.
This exploitation will broaden her horizons and be consistent with the Scientific way of looking at things.
Affectionately,
Alok Da
