It doesn't look from your summary, that you have considered how religion acts to keep people from becoming violent in societies where there is a lot of poverty and not good law enforcement.
Yes, the religion might condone violence against some outside group. In that way, it might channel people's desire for revenge for injustices that have been done to them, into violence that doesn't disrupt the society around them.
I wrote more about this in another thread.
If you want a kind and non-delusional society, arrange for social justice! And good medical care.
Africa just had another crazed faction of islam? er'... whatever.. kill agriculture students!@ BBC
ps Donald Barbera blogged recently about the book Out of America: A Black Man Confronts Africa, which tells of widespread political corruption, crime and violence in Africa.
It seems the widespread religiosity in Africa is probably related to this - that the religiosity seeks to control the corruption, crime and violence - in the absence of good law enforcement and a reasonably fair government, and in societies with a lot of poverty. And probably does control a lot of anger in individuals - as well as direct the anger towards outsiders.
Religion (however measured) is in sharp decline in the most developed countries that enjoy the highest standard of living for most of the people, namely social democracies such as Japan and Sweden. It persists in undeveloped regions like sub-Saharan Africa.
The perceived importance of religion (or religiosity) declines predictably with development (however measured), allowing one to predict how long it will take for religion to become unimportant for the majority of the global population. It will take approximately a quarter-century. This boils down to about a 1-percent decline of religiosity each year.
Why is the global population turning secular? To answer this question, it helps to understand the emotional function of religious beliefs and rituals. Religion calms distress and thus functions like the security blanket from which a child derives comfort when upset.
The market for religious comfort is strongest in the most miserable places in the world, where life is hard, life expectancy is short and life can be expunged at any moment by infectious diseases, violent criminals, starvation, brutal political leaders or natural disasters.
In the most advanced social democracies, the quality of life is much better, with expectations of good health and long life expectancy. There is less need of the security blanket of religion, and its emotional functions are supplanted by medication, psychotherapy, sport and entertainment.
So the answer to the question of whether atheism can replace religion is clearly "yes." It not only can replace religion but has done so in the most advanced social democracies, such as Sweden and Japan.
Here in the USA we are somewhere between Sweden and Africa: we're relatively affluent but citizens don't have as much security as in Sweden.