First I'll address the logical errors. The authors actually summed up their case for the existence of God quite succinctly on page 219 ...
"... it is simply not the case that we have argued in a circle or begged the question in the book. Theists don't say, 'God exists: therefore God exists.' Therefore, neither is our argument circular. If anything it's been structured thus:
A law of morality exists and is known to all --- and therefore, God exists. Consciousness exists, and the mind; reason, and the laws of logic; human worth, dignity, and equal rights; free will, human personality, love purpose, and meaning --- and therefore, God exists."
Now it doesn't take a philosophy major to see the major flaws in their logic ... like where's the proof for starters?! But in fairness to the authors their argument is a little deeper, but not much. Basically it is argued that atheists only believe in the natural world containing material items. However, non-material things exist like consciousness, laws of logic, morality, love, and so on. Since these non-material things exist then atheism is false and therefore the Christian God exists. Putting this into a structured logical argument leads to the following premises & conclusion:
- Atheists believe only in the natural material world;
- Non-material things exist;
- Therefore atheism is an incorrect world view;
- Therefore the Christian God exists.
OK, let's pick apart this argument. First, atheism is only the lack of a belief in a god. It makes no claim about the natural, supernatural, material or non-material world views. They are wholly separate philosophies. So being an atheist does not also mean being a materialist, and vice-versa. Therefore premise #1 is flawed and the whole argument is shot right from the beginning. However, there is another logical flaw. Even if atheism is the wrong world view, that doesn't mean the Christian God exists! The author would need to provide further evidence to show that their God exists and not one of the other thousands of gods worshiped by humans.
The logical flaws notwithstanding, what really irked me were the baseless, irresponsible, and absurd comments made by the authors which were nothing more than a feeble attempt to appeal to emotions but ended up showing their stupidity and immaturity instead. Here are some examples:
" This means out of a total population of some 300 million Americans, 30 million citizens doubt, or outright deny, the existence of God. That's a significant number of people who ... would be in a position to do terrible damage to society."
" ... if the atheist worldview were to be implemented across the board as the basis of societal policy (as it has been, in limited fashion, at times in the 20th century --- with disastrous results), you would definitely not want to live in such a society, so brutal, so tyrannical, and devoid of genuine goodness and beauty would it be."
"We contend that the denial of God's existence leads to the complete disintegration of not only morality, meaning, and human value and dignity, but the possibility of knowledge itself. The atheist worldview leads to foolishness."
"Atheism enables sociopathic behavior by claiming that human life has no intrinsic, transcendent value. That's why as atheism gains ascendancy in the West, there is a concomitant rise in barbaric, inhumane practices such as abortion, fetal stem cell research, cloning, infanticide, and euthanasia. Society's death spiral into darkness, despair, and nihilism is being propelled by naturalism."
"In the atheist worldview it's good for the strong to devour the weak, because that is how the evolution of the species progresses."
In regard to that last idiotic comment, atheism is actually silent with respect to evolution. Remember, atheism only posits that a god does not exist. Atheism is silent to whether evolution is true. Moreover, even though the evidence shows that evolution is true and that "survival of the fittest" played an important role in the past, that doesn't mean someone who believes in evolution also thinks that survival of the fittest is the best policy going forward.
Bottom line ... the authors are complete morons.