The background to this is that we are creatures that run on energy, namely electricity. Any physicist can tell you that a basic rule is that energy cannot be created or destroyed, merely transformed. If we think of our energy as being the basis of a soul then we can assume that our souls cannot be destroyed at death, therefore meaning the only other option for our soul is transformation.
If our conciousness is transformed along with the energy and somehow remains intact then death is simply the process of relinquishing a physical shell which breaks down into its component parts and again becomes part of the earth. The energy released will be used in other natural processes.
Even if the soul does not remain intact in a fashion there is nothing to fear from death as we have returned to the flow of energy that provides the fuel for the universe to contine, whether this means we become one with the cosmos or if we again are invested into a corporeal shell it matters little.