Uh.. Yeah, that's not exactly a new question. Philosophers have discussed that very topic for centuries.
Michael Sandel's book is probably a good place to start
Justice: What's the Right Thing to Do?: Michael J. Sandel: 9780374532505: Amazon.com: Books
SEP is also decent, albeit a bit dense and wonky
The Definition of Morality (Stanford Encyclopedia of Philosophy)
Morality is generally defined as that which tells us right from wrong. But what happens when we no longer follow a moral code? What happens when we lose sight of the value of life?
Just because someone does not follow
your specific moral code, that does not mean they do not follow
any moral code.
People who wish to take the time to try and save lives are convicted of minor crimes... etc
The relationship between ethics and the law is hideously complex, in no small part because there are certainly instances where a law is unjust (e.g. Jim Crow laws), and obviously such laws are also the loci of both political and moral disputes.
The same is true for the left. Whether they want to admit it or not, and they have used numerous methods of "justifying" the taking of the life of the baby (from claiming it is liken unto a parasite to calling it a zygote, fetus, etc., anything but a human being in its growth process). At the same time they will oppose unjust wars (and rightly so) that takes the lives of thousands of military personnel, and millions of civilians).
Or, you're just talking past your opponents, and begging the question.
You are starting with the premise that "a fertilized egg is a human life." Your opponents do not share that belief, meaning they do not in any way, shape or form, believe they are ending a human life. It's not an excuse, it's an actual belief. You will never get anywhere in those discussions until you understand that.
Thus, abortion ultimately isn't actually a moral question. It's a metaphysical one, which uses moral language and partisan posturing in an attempt to discredit and/or ignore one's opponents.
(In contrast, discussions of the death penalty and euthanasia are moral conflicts, as there is rarely any question that the individuals are conscious and competent adults.)
What is morality, and why have we as a society lost the meaning to the point that life is no longer precious, but a commodity to be traded upon?
I strongly disagree that contemporary societies devalue life. In many ways, I'd say we are a much more moral (and moralistic) society than in the past.
There is significantly less violence than in earlier historical eras (see Pinker's
Better Angels of Our Nature for a summary). We no longer live in an era of constant warfare, as was the case in most of the world almost right up to 1945. Europeans have gone from slaughtering each other and their enemies, with a ferocity that shocked Muslims during the Crusades, to verbal sparring over electoral representation.
We value the lives of our children much higher today than in the past; people are routinely lashed (verbally only, of course) for perceived failures to take proper care of their children. We routinely expect that the state will intervene if children are abused by their parents. We have developed all sorts of means to extend life, and it is often taken for granted that every method and no expense should be spared to extend life (even if doing so degrades the quality of one's life). We routinely reject policies like euthanasia because of the risks of abuse.
We have rejected monarchy, and place a higher value on rule of law and democratic representation; even the most totalitarian regimes in the world still try to pass themselves off as having elections. The very concept of human rights is only about 300 years old, and we obviously have much more respect for human rights and civil rights than in the past.
While criminal justice systems are not perfect, and solitary is still in wide use and inhumane, it's still obviously superior to past systems in which the use of torture to force confessions and testimony were routine, and where punishments ranged from brutal (e.g. lashings) to horrific (draw and quartering).
Thus, I must reiterate that the world has not descended into Mad Max-ian Madness because a large percentage of people disagree with you about abortion.