Abortion is deliberately intending the termination of pregnancy via death of the unborn, whether as an end or a means to an end. Any act that deliberately intends the death of an innocent human being, who has been created in the image of God, is intrinsically evil. 

Is the unborn human? 

There is no question that the unborn is a unique human with an entire lifetime's worth of potential ahead of himself or herself. Embryologist Dr. Dianne Irving writes; "Scientifically there is absolutely no question whatsoever that the immediate product of fertilization is a newly existing human being. A human zygote is a human being. It is not a "potential" or a "possible" human being. It is an actual human being - with the potential to grow bigger and develop its capacities." (Dr. Dianne Irving, "When does Life Begin? Scientific Myths and Scientific Facts", International Journal of Sociology and Social Policy, 1999) p. 6 

Is the unborn human a "person"? 

Absolutely. To use the classical definition; a person is "an individual substance of a rational nature". The unborn certainly qualifies as this. Other defintions of personhood that rely on some form of functionality are both arbitrary and often applicable to others already commonly recognized as persons. This "depersonification" of humans is an old evil trick humans have used as a pretense to eliminate other innocent "unwanted" humans. The Nazi treatment of the Jew as "life unworthy of life" is a good example. 

What if the mother has been raped? 

Some of the horrors and evils of rape lie in its brutality, its violation of another, viewing another as an object to be abused, lack of concern for their life and flourishing, etc. These things should never be done to another human being, and this includes doing it to the unborn. Interestingly enough, the above evils of rape apply to abortion. As in rape, abortion also devalues the unborn to the level of an object, shows a lack of concern for the unborn's well-being, and is very brutal. The appropriate response to such a horrfic act is not another horrific act, but rather love for both the innocent mother and the innocent child. Secondly, the question must be asked; does an innoecnt person who has been horribly violated then have the right to go and brutally violate another? Clearly not. An innocent third party ( the unborn child) should not have to suffer for the crimes of his or her parent. The appropriate response to rape involves loving and caring for the victims, not granting them a right to brutalize another innocent person. 

What if the life of the mother is in danger? 

Cases where a woman's life is endangered by her pregnancy are so rare as to
be virtually non-existent. However, in the case of such a dilemma, it would
still be WRONG to have an abortion because even if the mother may die
because of the child, this is not a sufficient reason to kill the child. We
oppose abortion for the reason that deliberately taking the life of an
innocent child is wrong, and ALWAYS wrong, and hence even if the life of the
mother should be in serious danger (which, again, is VERY VERY RARE), this
still does not suffice to overthrow the universally valid moral principle
that we cannot deliberate kill innocent people. The end does not justify the
means. In either case, somebody (either mother or child) will die, so we
must let nature take its course and suffer the death of the mother rather
than the child. But I must repeat again: a scenario like this is virtually
non-existent.
 

What is the moral logic of the Pro-Life position? 

Intentional killing of innocent human beings is wrong.
Abortion is the intentional killing of an innocent human being.
Therefore abortion is wrong.
This is a valid argument with a moral first premise and a factual second premise. The sound conclusion demonstrates that the pro-life position is in accord with right reason. 

Common Arguments and Responses

"Keep your laws off my body."
Answer 1: It's not about your body; it's about someone else's body, namely the baby's.
Answer 2: What do you mean, my laws? Moral laws are universal; they're not mine. Just like laws against murdering born people aren't any individual's laws, neither are laws against murdering unborn people. The pro-Life side can demonstrate the correctness of its positions irrefutably through science and reason.
Answer 3: Yeah, that's what the unborn baby says, too

Keep your "choices" off my body!"Every woman should have the right to choose what she does with her body."
Answer: It's NOT her body! The baby is in her body, yes, but not part of her body. The baby, from the moment of conception, has his/her own DNA and its very own and unique genetic code. This is impossible if the child is part of the mother's body.

"Everyone has a right to choose."
Answer 1: Choose what, please? The phrase "right to choose" is empty and deceptive if we stop there. Whether or not someone has a right to choose something depends on the object of the choice, i.e. what it is that we're choosing! There are many things we can't choose: we can't choose to do whatever we want and we can't choose to kill whomever we want, for instance. Duh!
Answer 2: It's a child, not a choice.
Answer 3: Somebody's right to choose something can never exceed someone else's right to live. The right to live is the first of all rights; no other rights can infringe upon it. The right to live can only be taken away by one's own actions, through being guilty of a very serious and heinous crime. All unborn children, however, are innocent and have commited no crime.
Answer 4: So everyone has a right to choose? Really? Can I choose to have slaves, too? The point is, choice falls flat when that choice involves harming innocent humans beings.

"Abortion is simply a reproductive choice."
Answer 1: <cough> Some "choices" are wrong. Women are free to make reproductive choices before they get pregnant (such as being chaste), not after. Once you're pregnant, that's it, no more choices, because then we're dealing with a human being, completely unique and separate, and all a mother's choices must bow to the sanctity of innocent human life.
Answer 2: In the 1800's, there were people in the U.S. who had slaves. On top of that, many punished their slaves and made them suffer. They could have called that a "property choice," since they believed that slaves were property, and what they did with their "property" was a matter of their own choosing. The point is: we must look beyond the rhetoric to see the reality of what is signified. You can call killing people (or making them suffer) all you want; the truth still remains that the action is wrong. Even euphemisms like "reproductive choice" won't change the facts, just like "property choice" changes nothing when it signifies wronging human beings.

[to a male:] "Have you ever been pregnant?"
Answer 1: No, but that's beside the point, because this issue is about what's right and wrong, moral and immoral, and these facts don't depend upon whether you are a man or a woman or whether you've ever been pregnant. To deny this amounts to saying that no one can say whether it's right to kill Jews unless he's a German Nazi, or whether it's right to have a slave unless he's a white American living during the time of slavery.
Answer 2: If males can't talk about abortion, then the Supreme Court ruling of Roe vs. Wade, which legalized abortion, is null and void, because the justices were all male.

"Women shouldn't be forced to be pregnant against their will." / "Women shouldn't have a compulsory pregnancy."
Answer 1: That's an argument from pity, and therefore fallacious. Since what's at stake in that "pregnancy" is an innocent human life, the baby's right to life overrides the woman's wish not to be pregnant. [An innocent human being's right to life, being the most basic of all rights and guaranteed by the Constitution, overrides any other rights or wishes.]
Answer 2: Everybody must take responsibility for his actions. If a woman does not wish to become pregnant, she shouldn't have sex. [Obviously, this argument doesn't work in rape cases.]

"The object of abortion is a fetus, not a child or a baby."
Answer: So what's a fetus, huh? "Fetus" is simply a term denoting an unborn child from eight weeks after conception until birth. Just like we use terms like "toddler" or "teenager" to refer to humans at different stages of development after birth, so also we use words like "fetus" and "embryo" to refer to humans at different states of preborn development. In short, a fetus is a child, simply at a preborn state of development. By the way, "fetus" comes from the Latin word foetus, meaning "little one."

"The object of abortion is a product of conception. It's tissue."
Answer 1: You and I, too, are "products of conception." And you bet we contain a bunch of tissue (especially if you're my weight!). But you are omitting a significant deal; in fact, so much that it changes the entire deceptive situation you have created through your rhetoric. The real question is: what is it tissue of? A human being! And no preborn child consists merely of tissue. Oh no. Very quickly, fingernails are present, hair develops, bones are starting to grow, etc. So you're wrong in saying that it's tissue because you are implying it's tissue only, kind of like just a bunch of cells clogged together and floating around. But that is not so, unless you wish to refer to yourself as just a blob of tissue, a product of conception.
Answer 2: The fact is that any human product of conception is a human being! Humans are--thank God!--naturally incapable of producing any offspring other than human beings. You'll never have a sheep or squirrel; it'll always be a human being, a baby.

"Don't like abortion? Don't have one!"
Answer 1: "Gee, don't like slavery? Don't have a slave!" --See how stupid that is?
Answer 2: "Gee, don't like pedophilia? Don't be a pedophile then!" --See how stupid that is? We can justify any crime this way.
Answer 3: If we know that an injustice is done to somebody, we have a moral obligation (!) to speak out and oppose this and try to end the injustice or right the wrong if still possible. [If you are talking to a person who professes to believe in the Bible, you can add Proverbs 24:11: "Rescue those who are being taken away to death; hold back those who are stumbling to the slaughter."] We must speak for those who cannot speak and defend those who are too weak to defend themselves.

[to a male:] "Have you ever been pregnant?"
Answer 1: No, but that's beside the point, because this issue is about what's right and wrong, moral and immoral, and these facts don't depend upon whether you are a man or a woman or whether you've ever been pregnant. To deny this amounts to saying that no one can say whether it's right to kill Jews unless he's a German Nazi, or whether it's right to have a slave unless he's a white American living during the time of slavery.
Answer 2: If males can't talk about abortion, then the Supreme Court ruling of Roe vs. Wade, which legalized abortion, is null and void, because the justices were all male.

"Quit showing those disgusting pictures of aborted fetuses. You're just trying to entice emotions."
Answer 1: Photographs aren't emotional. They just depict reality as it is. If this reality creates an emotional reaction in you, perhaps it should tell you something. So if you don't like what you see in those photos, it's because the reality of abortion is disgusting and wrong. That's not the pictures' fault, just like it's not a mirror's fault if it displays something you don't like when you look in it.
Answer 2: You didn't have a problem with anti-war Protesters showing photos of napalmed babies back during the time of the Vietnam war. The war ended much earlier because of those pictures. They showed that what was going on was wrong. If it wasn't wrong to show those pictures then, why should it be wrong now to show the even grislier reality of what is legal here in this country?
Answer 3: Funny you should bring up emotionalism. Because it's pro-abortion supporters like you who are actually arguing on emotional and therefore fallacious grounds. You are the ones who argue from pity, as in, "But look, she can't afford to have a baby right now" or, "But this poor woman was raped!" These are emotional arguments because they ingore reason (which tells us that being raped or not having time or money for a baby are not sufficient reasons to kill the child) and favor pure emotionalism and pity instead.