No, my definition of life is strictly scientific. Life is present when biological processes occur which are self-sustaining within their natural environment.
I already mentioned that for research purposes, I have grown countless human cells. I have subjected these cells to various poisons and I have genetically altered them. When I am finished with them, I kill them. The cells are verifiably human through any number of biochemical tests that confirm that their DNA and proteins are human. For as long as I provide food, water, oxygen, carbon dioxide, and warmth, they remain verifiably alive--they even exhibit behaviors. The fact that I have killed countless millions (maybe even billions) of human cells does not make me a murderer because those cells do not have the capability of developing into a separate human being.
From a strictly scientific point of view, life is an intrinsic and continuous property that is passed from parent to progeny during reproduction (one living cell becomes two living cells). Once life is gone, it cannot return. One cannot pick a point and say "That's where life begins" because, scientifically, there is no such point.
For a baby to be alive at birth, the baby had to be alive at every point prior to its birth. It simply would not exist had a living human sperm not united with a living human ovum to form a living human zygote. If, at any point, the germ cell/zygote/blastocyst/embryo loses the property of being alive, that property is gone forever and a living baby will not result. And non-human sperms and ova simply cannot produce a human zygote. (Do you seriously think that dead sperm will fertilize dead ova if placed together in a petri dish?)
At the point of implantation the embryo can now receive oxygen and nutrients and continue to grow into a baby.
Let's continue with science. At about 22 weeks current medical technology can preserve that human life outside the womb. There is some debate on this and what viability is, but science is arbitrary, too. Scientists are constantly picking and choosing hypotheses and then quibbling over the evidences. We can simply pick this time as the very latest date life begins.
That is contradictory. You cannot describe an embryo in terms that indicate it is alive (scientifically, if it is growing, it is alive) and then go on to say we could pick an arbitrary point to say it is alive. That is completely nonsensical and unscientific.
There are other points to discuss, but I just realized that I have to leave for work.
I cannot quarrel with your analysis of life as a scientific matter. The issues seem to arise when (at beginning and end points) we consider that life deserving of protection from destruction and entitled to support of its continued existence. There would seem to be many points along the spectrum that might be considered. Determination of and disagreement about the point of beginning and of end is what has created so many disputes, primarily in the realm of abortion “rights” and end-of-life matters...
That's my exact definition, so how can we come to differing conclusions? Because you're practicing a type of scientism in an attempt to leave God or human spirituality out of it. This method is wholly incapable of answering any of life's serious questions.
You couple this with a type of halo effect over "scientific" explanations and definitions you agree with. This is serious bias. Look at your very next paragraph:
For as long as I provide food, water, oxygen, carbon dioxide, and warmth, they remain verifiably alive
Clearly, that's not the natural environment of human cells. Do these cells naturally seek you out? Do they normally occur in Petri dishes? So you've just violated your own definition. They may be cells from or of humans, but they're not human beings. You've not grown and killed numerous human beings have you? Of course not, so what are we discussing here?
My point is that as a Christian and given my beliefs it makes the most sense that a human zygote becomes a human being when the physical part of its humanity attaches to the uterine wall allowing it to meet the operational definition of life that you state above and that I accept. It is at this point that God would give it a spirit thereby completing it's humanity. If one leaves the spirit out of the equation you don't clarify, but muddy the waters.
Are you familiar with Genesis Chapters 1-3. They would be worth discussing particularly in this context.