A very good question, but over simplified. I have Googled this to find some interesting numbers and they would seem to hold to the questions initial premise. Further, to substantiate this, is my own experience as a military and civilian police officer. In the 12 years 60's 70's, as a sworn officer and numerous arrests, non-religious was never noted on the booking sheet, Christian or Catholic were the designations of choice. That was changed in the mid 80's after a night of drinking, Hank Williams, a woman, a pool hall and a couple of disagreeable people, as I found myself noting non-religious on my own booking slip. Those were the days, but then, I digress.
The below quotes are interesting and although difficult to substantiate, I would have to agree with them.
"If all the Atheists & Agnostics left America, they'd lose 93% of The National Academy of Sciences & less than 1% of the prison population."
— Ricky Gervais (@rickygervais)
"75 percent of Americans are God-fearing Christians; 75 percent of prisoners are God-fearing Christians. 10 percent of Americans are atheists; 0.2 percent of prisoners are atheists.
I don't know that this is do to the assertion that Atheism makes a better human being, but, in my experience, it makes one who is less prone to follow. Atheist are greatly independent in action and in thought and do not seek approval through peers, which, especially today, seems to be a driving factor in much of our crime. Drugs, gangs, government and the social push to categorize, engineer and control our young people are driving factors in dysfunction. We seem to be destroying the individual to a collective, destroying the family unit, minus a father, to a government defined franchise dependent on government morality, which of course, is an oxymoron or a contradiction in terms.
Brought up in a Catholic home, but embracing Atheism at the early age of 14 or so, I found Catholicism (Christianity) comforting in many ways and even today I feel that such a "family" centered environment is the best for the raising of children. I, in turn, raised my children, all successful adults in such an environment, minus the religion, but embracing the strength of the family, of the male and female attributes of a mother and father providing that critical balance so necessary.
Certainly, Atheism has no great promise of and by itself. It is merely a statement. What matters is the individual and it is the individual child, not a human resource to be herded.