Among Christians, the moral arguments is one of the most popular philosophical arguments for God’s existence. The arguments goes something like this:
Real moral obligation is a fact. We are really, truly, objectively obligated to do good and avoid evil.
Either the atheistic view of reality is correct or the “religious” one.
But the atheistic one is incompatible with there being moral obligation.
Therefore the “religious” view of reality is correct.
The atheist’s answer to using moral precepts to argue for God’s existence is to argue that God can’t possibly exist. All you have to do is look at the evil in the world. If God does exist, He would never tolerate this evil. Former atheist Antony Flew cited this problem as one of the reasons he became an atheist so early in his life.  Bertrand Russell also argues similarly:
When you come to look into this argument from design, it is a most astonishing thing that people can believe that this world, with all the things that are in it, with all its defects, should be the best that omnipotence and omniscience have been able to produce in millions of years. I really cannot believe it. Do you think that, if you were granted omnipotence and omniscience and millions of years in which to perfect your world, you could produce nothing better than the Ku Klux Klan or the Fascists?
A frequent Christian response to this objection is that the atheist actually reaffirms the validity of the Christian argument. Why are atheists sure they are actually referring to objective precepts not to do evil? For instance, is genocide or bigotry objectively evil and morally wrong or is that mere opinion? Atheists can only object to the evil in the world if there is an objective moral code that transcends humans. Such a source for that can only come from a divine source.
An interesting different approach to this problem has been recently undertaken by Norman Geisler and Daniel McCoy in their book The Atheist’s Fatal Flaw.They explain that the atheist position contains a fatal contradiction in that atheist philosophy does not allow God to act to contain the very moral evil atheists want prevented.
Geisler and McCoy explain there are three ways God can prevent moral evil. Method A posits God could prevent all moral evil. Method B posits God could intervene to prevent only the worst moral evil. Method C posits God could intervene only in the area of one’s conscience.
Preventing moral evil, then, must involve in some capacity the ruling of other people’s actions – whether taking away all free will and making people nothing but robots or causing indirect control over people using guilt that results from sinful actions. However, as Geisler and McCoy explain, atheists value autonomy above everything else in five areas that define one’s worldview: origin, identity, meaning, morality, and destiny. Let me explain each. Atheists do not need or want God to be involved in creating because humans, they believe, sprang from a purposeless process of evolution. We got here without God’s help. Atheists also demand they decide for themselves what their purpose in life is or their value. Atheists also want to choose what moral codes to follow. Atheists and humanists both explain that our moral codes were a result of social evolution over millions of years. We learned proper moral behavior, but proper behavior is always subject to change. This is what Christian philosophers call moral relativism. Lastly, atheists often state that whatever problems exist in humans their fix does not in any way depend on faith in or acceptance of God’s existence or anything God demands of us. Rather, faith in science will allow us to fix these problems. Again, I cite atheist Bertrand Russell whose hopeful formula is echoed in Humanist Manifestos I and II as well.
Science can help us to get over this craven fear in which mankind has lived for so many generation. Science can teach us, and I think our own hearts can teach us, no longer to look around for imaginary supports, no longer to invent allies in the sky, but rather to look to our own efforts here below to make this world a fit place to live in, instead of the sort of place that the churches in all these centuries have made it.
Chapter three of their book begins explaining, in my opinion, a much ignored area of philosophy: the ways God controls moral evil while allowing for personal freedom. As Geisler and McCoy explain, in each of these areas the atheist prefers freedom to God having any control over our actions. For instance, God wants us to submit to Him, but atheists believe God is a tyrant for demanding such obedience and McCoy quote Dawkins and Christopher Hitchens as suggesting humans don’t need policing. God works through our conscience, but atheists often say that humans do not possess responsibility for their actions or they posit that they have done nothing immoral at all. This, I believe, is one of the main reasons atheists believe in materialism; they want to eliminate any chance of humans being responsible for their actions. If humans are merely physical automatons controlled by nothing but material substances, they can no more control what they do than a rock can control whether it rolls down a hill. Death is allowed by God because it limits human evil a person can do, but atheists claim God is immoral for allowing that as well.
Reading their book, it’s obvious that atheists want to have their cake and eat it too. Actually they are more like the child who demands the keys to a parent’s car even though they cannot drive, get in an accident, and then blame the parent for giving them the keys. Such a child is rebellious and refuses to accept any parental control. In regards to what God wants us, this is sinful rebellion which is how we would expect unbelievers to act if Christianity is true – which is one more reason I believe it.
 Peter Kreeft and Ronald Tacelli, Handbook of Christian Apologetics (Downers Grove, IL: Intervarsity, 1994), 72.
 Antony Flew, There is a God (New York: HarperCollins, 2007).
 Bertrand Russell, Why I am Not a Christian (New York: George Allen & Unwin Ltd., 1975), 10.
 Norman Geisler and Daniel McCoy, The Atheist’s Fatal Flaw (Grand Rapids: Baker House, 2014). All citations from this essay are from this book unless otherwise stated.
 Russell, 22.