How much pain can atheists withstand ?

[Fake Messiah]

Many children starve when resources are not scarce

All resources are scarce, a decent lunch doesn't grow on trees. So, again, children starving to death is completely fine, even beneficial, from your worldview. There are many intellectual heavyweights in this world defending eugenics, and not without reason. Atheism as a perverted outlook on life makes this task even easier.

Let me reformulate that more sharply : the total quantity of available goods to the human species is constant, so less people alive means more available goods for everybody.

You obviously don't know Boru's worldview, and you are using a Naturalistic fallacy:
"The naturalistic fallacy is the idea that what is found in nature is good. It was the basis for social Darwinism, the belief that helping the poor and sick would get in the way of evolution, which depends on the survival of the fittest. Today, biologists denounce the naturalistic fallacy because they want to describe the natural world honestly, without people deriving morals about how we ought to behave (as in: If birds and beasts engage in adultery, infanticide, cannibalism, it must be OK)." — Steven Pinker