The problem with moral absolutes is that there are so many to choose from! On the other hand, you can explain in plain, rational English (without resorting to religion) why you think abortion is immoral and destructive to society. Why not have both your moral absolutes and your faculties for reason?
There are some basic moral absolutes which are common to all monotheist religions, and even some which aren't like Buddhism.
I'd list the basics as:
No murder.
No fornication. (Which includes other sexual vices such as sex with children, incest, same sex acts, bestiality, and so on.)
No adultery.
No theft.
No lying (especially in court or as a public statement.)
And then there's ones such as:
Respect the elderly.
Protect the helpless.
THese are off the top of my head. I am naturally familiar with the 10 Commandments; I am also famliliar with the Yamas and Niyamas of Patanjali's Yoga Sutras, the Vedic system of morality, and have a passing knowledge of Buddhist ethics. Judaic morality as written in the Torah is the same as Christian morality.
Abortion? It's wrong to murder. But if someone rejects moral absolutes as given in the religions of the world, there's nothing at all with which to refute Peter Singer. If you aren't familiar with him, do a FR search.
I'm not advocating that all the above should warrant jail sentences when not followed. But if the "don'ts" are encouraged and glorified, and the "do's" are disparaged, then everything goes to hell in short order.
I've always thought they were pretty well defined.
- stealing is wrong...murder is wrong...infidelity is wrong...etc
On the other hand, you can explain in plain, rational English (without resorting to religion) why you think abortion is immoral and destructive to society
No you can't because religion, in this case the Law of God, is the prevalent factor in determining just why abortion is wrong.