The moral argument goes this way;
- Every law requires a Lawgiver
- Objective Moral Law exists
- Therefore there is an objective Moral Lawgiver
Let’s examine the first premise- Every law requires a lawgiver. We know experientially that no law just comes into existence without introduction by a personal being. The laws against drunk driving, terrorism didn’t just pop into existence, they were introduced by people.
Unto the second premise- Objective moral Law exists. Objective moral law refers to the fact that every person recognizes some moral code (that some things are right, and some things are wrong). Every time we argue over right and wrong, we appeal to a higher law or standard that we assume everyone is aware of, holds to, and is not free to arbitrarily change. To say that there are objective moral values is to say that something is right or wrong independently of whether anybody believes it to be so. It is to say, for example, that torturing babies is morally wrong or that Nazi anti-Semitism was morally wrong, even though the Nazis who carried out the Holocaust thought that it was good; and it would still be wrong even if the Nazis had won World War II and succeeded in exterminating or brainwashing everybody who disagreed with them. Attempts to refute moral objectivity are often done with the- “you like vanilla, I like chocolate” analogy, but this is a misunderstanding of the premise. The premise doesn’t state that everything is objective, obviously some things are relative, but all it takes for premise two to be right is for just one thing to be objectively wrong.
From this we can deduce that, if you believe in the reality of objective morality the existence of an objective, unchangeable, moral lawgiver is rationally inescapable. However, if you go down the path of moral relativity as so many famous atheists have, then I hope you see the disharmony between reality and the world created by your intellect. A clear example; If you’ve ever pronounced or felt it was wrong when someone stole something from you, well that’s objective morality right there. The fact that you believe that someone else OUGHT not to take what’s yours without your consent already shows you subscribe to objective morality.
It seems to me that on an atheistic worldview objective morality can’t be justified or properly grounded. If we are just overgrown germs then there is no objective morality, meaning that whether torturing babies is bad is just a matter of opinion, whether the holocaust was immoral is just your opinion against Hitler’s. Whether someone stealing from you is wrong is just your opinion, you might feel sad about it, but the culprit feels good. If we are just molecules in motion we don’t have free will, we’re just reacting to physical causes, and our actions are just like a fizzing can of coke. When someone steals or lies who has he offended, the carbon molecules? This sort of thinking makes the idea of responsibility illusory. Please do not misunderstand my point, I am in no way saying that atheists do not know morality or that atheists are evil people. Actually I have met and know so many atheists who are beautiful and caring people. This is not shocking to me, as in the bible it says that on every human’s heart is written a standard moral code-Romans 2:15. However, I would say that without the existence of God, morality cannot be truly grounded; as every act would just be a matter of opinion. In the wild when a male lion kills the cubs of a lioness in other to propagate only his genes, we don’t consider that immoral or wrong. However, we say that it is absolutely wrong for a man to kill a child, because we attributr an intrinsic worth to every human.
Many theists and atheists agree on the point that, without God there is no objective morality, everything is relative. For example, the late J. L. Mackie of Oxford University, one of the most influential atheists of our time, admitted:
“If . . . there are . . . objective values, they make the existence of a God more probable than it would have been without them. Thus, we have a defensible argument from morality to the existence of a God.” 
But in order to avoid God’s existence, Mackie therefore denied that objective moral values exist. He wrote,
“It is easy to explain this moral sense as a natural product of biological and social evolution . . ..”
Michael Ruse, a philosopher of science, also agrees. He explains,
“Morality is a biological adaptation no less than are hands and feet and teeth. Considered as a rationally justifiable set of claims about an objective something, ethics is illusory. I appreciate that when somebody says “love thy neighbor as thyself,” they think they are referring above and beyond themselves. Nevertheless, such reference is truly without foundation. Morality is just an aid to survival and reproduction . . . And any deeper meaning is illusory”. 
However, for the sake of discussion let’s say evolution is true. Evolution is only descriptive and not prescriptive, it tells us what survives but not what ought to survive, it tells us what we do (sociology) but not what we ought to do (morality). Since, evolution is a process of change it means that there’s a probability of rape or torturing babies being good at some point in the future. Just take your time to think about that for a moment, that your kids or grand-kids might live in a world were rape is good.
Tim Keller in his book ‘The Reason for God’ insists that morality could not have arisen by evolution:
“Today we believe that sacrificing time, money, emotion, and even life—especially for someone ‘not of our kind’ or tribe—is right….How could that trait have come down by a process of natural selection? Such people would have to have been less likely to survive and pass on their genes….Natural selection does not work on whole populations.”
Also, altruistic behaviour, by definition, is not in one’s own interests. The extreme of altruism—consciously giving up one’s life in order that others not related to you might live—cannot be the result of conditioning through natural selection. Those who give up their lives for others are eliminated from the gene pool. Extreme self-sacrifice is a trait that natural selection not only does not encourage, but should even eliminate from society. The selfish are more likely to survive and reproduce than are the selfless. Yet selflessness is praised as a virtue pretty much in every existing society, from the west to east. From Kyle Carpenter (a 24-year old marine who jumped on a grenade to shield his comrade), Martin Luther King (a civil rights activist who was eventually assassinated at age 39 for his fight against racial inequality), William Wilberforce (who campaigned against slavery, and helped to outlaw slavery in Great Britain. The Slavery Abolition Act 1833 was passed three days after his death). Nelson Mandela (imprisoned for 27 long years for fighting apartheid in South Africa), Mahatma Gandhi (Inspired Indians to independence through a path of non-violence, he often took long fasts as a means of social protest. He was later assassinated for his views on non-violence). Malala Yousafzai (A young Pakistani schoolgirl who was shot in the head at close range by Taliban in order to end her campaign for women’s right to education, but she survived) and there are many more examples, but I’m sure you get idea. We also observe that nature is ruled by one central principle—violence by the strong against the weak. This was Hitler’s rational- he felt that if the weak did not want to fight they didn’t deserve to live. In his book titled- Mein Kampf (My Struggle), Hitler stated;
“Those who want to live let them fight, and those who do not fight in this world of eternal struggle do not deserve to live”
To me that sounds a lot like the theory of natural selection. Hence, our moral sense cannot be evolutionary because it is contrary to nature.
Therefore, if you believe human rights are a reality, then it makes much more sense that God exists than not. If you insist on an atheistic worldview and yet you continue to pronounce some things right and some things wrong objectively (regardless of who does it or who it is done too), then I hope you see the deep disharmony between the world your intellect has devised and the real world. This leads us to a crucial question. If a premise ‘There is no God’ leads to a logical conclusion ‘that whether torturing babies is wrong is culturally relative. A conclusion I’m sure you know in your heart is objectively wrong as a decent human being, why not change the premise?
In summary, the logic for God is so overwhelming that the philosopher/theologian R. C. Sproul insists that a reasonable man must acquiesce to this conclusion;
“The evidence is so compelling, that one must override his senses to deny Him. It is only the person who is blinded by his own agenda that refuses to accept it. A thinking person who denies God must do so on the basis of preferring to believe there is no God in order to try to escape His judgment, thus irrationally seeking autonomy. Our challenge to the skeptic: At some point you must be willing to rationally consider the evidence and honestly seek with an open mind details about the God who made you.”
 J. L. Mackie, The Miracle of Theism (Oxford: Clarendon Press, 1982), pp. 115-16.
 Ibid., pp. 117-18.
 Michael Ruse, “Evolutionary Theory and Christian Ethics,” in The Darwinian Paradigm (London: Routledge, 1989), pp. 262-269.