Death???

I was contemplating the death of a loved one today and it occurred to me that both Christianity and eastern Mysticism agree that there is no real death.   We have two births: one into this life and one into the other.  As this is the realm where we have the illusion of time and space and we are mortal, this is the dream we awaken into.  Ou real existence is on the other side where we have no time and space and we are eternal.  So, why do we cling so had to life on this side..the temporary side?  I am sure there is a reason and I think one of then is that we must be deep in the illusion for it to work.  In an enlightened state, we would just see death as a doorway between the worlds