As someone who has lost a child, I can understand why Terri Schiavo's parents tried to keep Schiavo's body alive. What's harder to understand is why they worked so hard to keep her out of heaven for so long. My tentative hypothesis is that, for all the tenure and firmness of the grip that religion has on humanity, individual humans are intuitively skeptical that there is an afterlife. One way to check your intuitions about heaven is to consider the following questions:
If on Earth you tried but couldn't have a child, can you have one in heaven? If you had a miscarriage on Earth at ten weeks' term, is the child waiting to meet you in heaven? What about discarded human embryos? What about stem cells? If you were a fetus or infant or child at death and get an adult's mind in heaven, what determines your personality? If you were mentally disabled or senile when you received life everlasting, do you get an adult's mind? Are some people in heaven still smarter or funnier than others, or is everyone equally intelligent and witty? Is there humor at all in heaven? Will any joke still seem funny after 100 trillion years? Will you understand (or be able to learn) every principle of math and science? Will you eventually understand everything, and thus face an eternity of having nothing new to learn? Will you know (or be able to learn) every fact of the history of you, your loved ones, humanity, and the Earth in general? Will you know Earth's future, or be able to observe it as it happens? Will others in heaven know (or be able to learn) embarrassing things about your life? Will you be able to remember any sinful pleasures of your mortal life? Will your memory of your sins be wiped clean, or will you still have shame? Will you be able to play games (like chess) with other people in heaven? Will you ever lose? Can you ever improve at such pursuits? Will you be able to take naps, and if so for what duration? Will people ever have differing opinions, interests, or hobbies? Will there be any possible way to create new knowledge or new art? What intellectual person could be happy having an omniscience withhold knowledge from her? What intellectual person could be happy being omniscient and having nothing left to learn?
Will you have a material body in heaven? If so: Will you need to eat and use the bathroom? Will you be subject to the periodic reproduction-related episodes which our bodies experience on Earth? If you were obese all your life, will you be slender in heaven? If you were a bodybuilder, will you keep your muscles? Can you decide to start bodybuilding in heaven? What are the physics and topology of heaven? Is heaven infinitely big, or does it have an edge? Is there gravity? Do heaven's physical laws govern everyone there who isn't God? Is there conservation of mass-energy and momentum? Is there entropy and friction? Are there any material scarcities in heaven, or does God provide an unlimited supply of any material good you desire?
If there are scarcities, then: What are the economics of heaven? Is there an official currency? Is there private property in heaven? What is the discount rate in heaven? I.e., is there a time-value of money, or are all interest rates zero? Is there technology in heaven? Is there capital equipment to help you produce scarce things more efficiently?