Michael P (an atheistic apologist) said this:
The happiness and suffering of other human beings matter such that we should all seek, whenever possible, to increase their happiness and decrease their suffering. Morality is required for human social structures and human communities to survive. Neither the presence nor the absence of any god can change this. Morals were in place long before the Judeo-Christian beliefs came into being. While religious theists may find that their beliefs impact their moral decisions, they cannot claim that their beliefs are prerequisites for making moral decisions. That is called the Appeal to Belief fallacy. Nor can they claim that being an atheist prohibits the employment of moral thoughts, acting in a moral way, and/or making moral decisions. That too is fallacious and known as Ad Hominem.
If you want to present an argument about the morality of abortion, please, by all means, do so. It is a valid argument. One that I struggle with, as do many “believers” that I know. But to generalize about atheists at the level you have and to use both the Ad Hominem and Appeal to Belief fallacies removes your credibility. Adding fuel to fear tactics is also very unappealing.
But Jonathan Sarfati (a Christian) countered the atheist with this:
I am very familiar with logical fallacies—see my paper Loving God with all your mind: logic and creation.
But you have misunderstood our “moral argument”, which is further explained in Bomb-building vs. the biblical foundation:
Our argument is not that atheists cannot live ‘good’ lives, but that there is no objective basis for their goodness if we are just rearranged pond scum.
Also, from a biblical perspective, morals predated societies. God gave Adam a command when he was the only man alive. Cain committed the first murder, then afterwards built the first city.
Also, in What is ‘good’? (Answering the Euthyphro Dilemma), I’ve asked:
The Euthyphro Dilemma can be turned around on atheists: Do you approve of an action because it is good, or is it good because you approve of it? If the latter, then your moral standard seems to be subjective and arbitrary, so you complain about God’s alleged arbitrariness. And if the former, then you are back to explaining where this objective moral standard comes from. As shown above, evolution can’t provide this, so the above Divine Nature Theory is back on the table.
Similarly for social theories of good—is something good because society makes a rule about it, or does society make a rule about it because it’s good?
The above Logic paper also presented a sound argument against abortion.
Sarfati, J. (2012). Abortion ‘after birth’? Medical ‘ethicists’ promote infanticide. Creation Ministries International. Available http://creation.com/abortion-after-birth. Last accessed 6th Jul 2015.