The Moral Argument for the existence of God is as follows:
1. Every law has a law giver.
2. There is a Moral Law.
3. Therefore, there is a Moral Law Giver.
If the first 2 points can be verified, then the 3rd logically follows. Obviously, every law has a law giver. For a law to even exist or be discussed it had to have been created. There can be no legislation unless there's a legislature. 
However, is it reasonable to believe that a true absolute Moral Law exists? I submit that it is and that to believe otherwise could result, and has resulted, in morally reprehensible consequences.
The idea of a Moral Law is impressed into mankind. For example, we know that love is superior to hate. We applaud and revere those who work to save lives, feed the poor, or care for the sick. Try to imagine a world were those celebrated were the ones that murdered others in cold blood, starved the poor, or discarded the sick. Or, as C.S. Lewis wrote in his classic work Mere Christianity:
"Think of a country where people were admired for running away in battle, or where a man felt proud of double-crossing all the people who had been kindest to him. You might just as well try to imagine a country where two and two made five." 
All of us know that there are absolute moral obligations. Who in their right mind would suggest that rape should be legalized? An absolute moral obligation is something that is binding on all people, at all times, in all places. And an absolute Moral Law points to an absolute Moral Law Giver. 
Let us imagine for a moment what a life could be like if someone decided to truly embrace the idea that there are no moral obligations in this world. Let us envision a life lived out, fully embracing the idea that there is no Moral Law or Moral Law Giver.
I believe that the late Health Ledger's performance as the Joker in the film The Dark Knight gives us a hint of what a life could look like if one truly adopted the idea that no Moral Law exists.
Ledger's performance is eerie, unnerving, and brilliant. The Joker, most likely the number one comic book villain of all time, fully embraces the idea of anarchy and chaos. He concedes as much:
"The only sensible way to live in this world is without rules."
As a result, the Joker leaves a wake of destruction, murder, and social disorder wherever he goes and views his existence as a kind of giant social experiment. He himself states, "You'll see, I'll show you, that when the chips are down, these uh... civilized people, they'll eat each other."
The scary thing about the Joker's philosophy of "living without rules" is that if there is no God, no one would be justified in claiming whether or not he is right or wrong. If there is no objective, transcendent source of the Moral Law in which we can look to as our moral compass, isn't "living in the world without rules" okay? If not, why? Or, how do we know?
As Francis Schaeffer rightly points out, a world with no moral absolutes leads to confusion and an inevitable moral vacuum:
“If there is no absolute beyond man’s ideas, then there is no final appeal to judge between individuals and groups whose moral judgments conflict. We are merely left with conflicting opinions.” (4)
For those who would deny that an objective moral standard exists, one only needs to treat them poorly and watch their reaction! However, I do not recommend this, but only mention it to bring about a point.
The non-believer may object by stating, "One doesn't have to believe in God to live a moral life!" I could not agree more! The Apostle Paul tells us the reason a nonbeliever can live a moral life:
"So, when Gentiles, who do not have the law, instinctively do what the law demands, they are a law to themselves even though they do not have the law. They show that the work of the law is written on their hearts. Their consciences testify in support of this, and their competing thoughts either accuse or excuse them..." (Romans 2:14-15, CSB).
Atheists cast aside the very foundation of goodness-God, who created them and who is the highest Good. 
The problem for the nonbeliever is that they have nothing in which to solidify why they believe love is better than hate. Or why saving a life is better than taking one in cold blood. Their conscience simple is and their atheistic worldview cannot explain where the feelings come from, why they exist, or if they even matter. Logically then, the question must be asked: "If we are not morally responsible to a Creator, why choose the better virtue?" If killing someone gets one to where they want to be and the guilt they feel afterward is simply a feeling brought about by naturalistic causes, then why not just dismiss those feelings? If you can avoid being penalized by the existing law system, why not "introduce a little chaos," as the Joker recommends?
The reader at this point maybe wondering, "Does this guy realize that The Dark Knight is based upon a fictional work and that the Joker isn't a real person?" Of course I do, however, I believe the films focal character offers insight into what a life could look like (minus the make-up and the funny suit!) if one were to truly embrace the idea that life has no meaning and that God does not exist. It has been rightly stated that if God does not exist, all is permissible...
Yes, The Dark Knight is a fictional film. Much like a world without an absolute Moral Law is fictional.
Without God, morality is merely subject to the whims of mankind’s feelings, opinions, and agendas. Our thoughts and feelings of right and wrong are products of one long string of meaningless chemical accidents, so why should we trust them or heed them? Reason becomes meaningless, life becomes meaningless, and morality becomes meaningless.
Those who hold to atheism and live a “moral” lifestyle live above the conclusions of their worldview; however, their worldview cannot justify nor sustain their actions. God alone provides us with an Objective Moral Compass.
Courage and Godspeed,
Chad A. Gross
1) Norman Geisler and Roman Turek, I Don't Have Enough Faith to be an Atheist, p. 171.
2) CS Lewis, Mere Christianity, p. 19.
3) Geisler and Turek, Ibid, p. 171.
4) Francis Schaeffer, How Should We Then Live?, p. 145.
5) Paul Copan, What Is the Natural Law?, The Apologetics Study Bible, p. 1683.
For Further Reading on The Moral Argument for God, please see:
1) http://www.biblicaldefense.org/Writings/moral_argument.htm- The Moral Argument by Phil Fernandas.
2) http://www.leaderu.com/offices/billcraig/docs/meta-eth.html- The Indispensability of Theological Meta-Ethical Foundations for Morality by Dr. William Lane Craig
3) http://christiancadre.org/member_contrib/cp_moral.html- Is it Possible to be Good Without God? by Christopher Price