What is the cause of death?
The short answer is: The cause of death is birth, because we are born we will die.
The complex answer is that everything in the world is temporary and changes. Everything is also inter-related and inter-connected (Karma).
Thus, the causes and conditions that allow us to be born comes together, and we call it birth. We all undergo constant changes in this world. This is what makes life limited and temporary (no one lives forever).
Then there is that change called death which is really all part of the whole that we can call the cycle of birth and death. In turn, each of us affects those around us.
Thus, what is important and to be valued is this time while we are alive, we call it life.
And what does that mean? Perhaps, we can leave this world in a better condition that when we came into this world. It is not the physical wealth that we accumulate while alive, but what effects do we have on others that gives value and meaning for our limited time on this spaceship called Earth.
As a Buddhist, we are not afraid of death, but no one wants to die. But realizing that our time is limited is exactly what gives us the freedom to really live. To a Shin Buddhist, realizing that our human life is limited gives rise to the feelings of gratitude which in turn is expressed in actions of kindness.
Gassho (with palms together), Rev. Ron