Human expiration dates

I'm not really sure how to address this topic. It's one I've given a lot of thought to over the years. But how does one go about when speaking on human mortality?
I've always seen the job of the priest and the job of the physician as opposites. The physician's job is to prevent death and to keep it as far away as possible. The priest's job is to prepare people for death, to teach them how to accept the reality of it.
A basic part of our biology teaches us to fear death. And for most of us, we also fear that there may just be nothing after death after all. If this was your outlook and fear, there's no wonder that you would work so hard to prevent death. So, from the time of Hippocrates we've been trying to delay death as well as we could. Within the last hundred years, we've eradicated polio, malaria and tuberculosis (in the US). We've increased our life expectancy so much that i continually climbs. But now, rather than dying of pneumonia or influenza, we die of cancer and heart disease.
My theory is this: human beings have built into them an expiration date. We all die at some point. All our medical advances have one goal in mind: immortality. We try to prolong our lives as much as possible, by putting death off indefinitely. But this is not our purpose. We were not designed to never die.
So, should we really be continuing on this endless quest for godliness? In my previous post I briefly made comment about some doubts about the Bible. One such doubt circles around the story of the Tower of Babel. However, even if I doubt the validity of the historic virtues of tale, it does have a lesson to be learned, as all passages of Bible have. The Tower of Babel teaches us not to try to exalt ourselves to the position of God. Humankind was not designed to try to take what God has set aside for Godself. We are not going to achieve immortality.
That being said, we should not despair either. If we all die, we all meet the same fate. In Pascal's words, we either disappear into nothingness, or fall into the hands of a wrathful God. I don't hold as much to the wrathful part, but I do think that we will end up in a similar place no matter who we are. A lot of Medieval pastoral theology focused on providing the hope for a better life for those who do lived seemingly meaningless lives.
But we haven't moved that far from the Middle Ages. Thanks to Nietzsche and the existentialists, we have another reason for considering our own existences. Kierkegaard emphasized the fact that we are hurtling uncontrollably towards our own deaths.
I don't wish to say there is no merit to medical technology or advances. Rather, I think we should turn our focus from living longer to living fuller.