Your assertions are so absurd that I don't even know how to respond, other than the say EMPATHY.
Your belief that we need some sort of a deity to care about people is so far from my experience, that I find myself just angry and baffled.
First of all, (and I've said this before) I care about human beings and the quality of life of human beings BECAUSE I don't believe that there is a shiny afterlife awaiting the suffering. Therefore, I have dedicated my life to working with marginalized people, many of whom are refugees, some torture survivors, to help them build a new lives for themselves. To help them find a sense of accomplishment. Joy. To try and leave pain behind and move on. Furthermore, I have worked to support policies of fair migration, just food distribution, safe working conditions, etc.
On a personal level, I have been through a period of extreme personal pain. Not pain for myself, but pain for people I care about. In a three month period, two sets of friends have buried their children. One innocent three year old hit by a car. And a promising 25 year old whose sudden death has shocked his friends and family. As I prepared my "happy winter break" activities with my own daughter, (ear piercing, Rockettes, baking cookies to share with neighbors, museum trips, presents and playdates and afternoons cuddling in front of a movie at home) what should have been a joyous time for me and my family was overshadowed by the pain of the loss of these human beings.
In between happy family activities, I struggled to make contact everyone who was not out of town, and let them know about funeral arrangements and the times and dates of the wake, the funeral service and burial for this sweet young man who died so young. I frantically arranged childcare between Christmas and New Years so I could attend these events. And many mornings I woke up weeping, and then put on my happy face because my daughter deserved a mommy who was prepared to give her all of the attention and fun and love that she had anticipated having during her week and a half off from school. And the whole time I felt the guilt of having such a loving, wonderful, happy family, at a time in which one family I know was suffering the loss of their toddler, and another family was suffering the loss of their loving, gentle son.
Why would I, as an atheist, be experiencing this range of emotions? Why would I give a shit about my daughter's joy or my friends' pain?
Because human beings are programmed to feel empathy. Some of us are wired wrong. But most of us care about the welfare of the people around us. We care most about the people who are closest to us. And mass tragedies may (like what is going on in the Congo right now) are beyond our comprehension. But the more we learn about other human beings, the more we care. We even cry for fictional characters in tragic books or movies. Even atheists do.
It is absurd to say that in the absence of religion, people would start harming each other indiscriminately.
So just stop this bullshit.