As an atheist and a materialist, Jimmie would be hard-pressed to provide a situation in which killing a child would be intrinsically bad. After all, if we're all just puffs of smoke with no souls, no eternity, who are just destined to turn back to dust when we die and be forgotten, then really, what does it matter what happens to any of us?
If they used their minds for logical discernment they would realize their worldview demands that they can believe in nothing. Why would you believe in anything which results from the chemical-physical processes of a mass of gray matter where electron potentials are depolarized across semipermeable membranes. Chemicals don't reason....they react. So they can give no reason supported logically for believing anything. In their world there is no reason to believe anything is good or bad or right or wrong or human rights or justice or injustice or any way to measure moral difference or truth. Things just are in the materialist worldview. To bludgeon a baby to death, in a materialists worldview, is no different morally than to pick an apple. Every act is determined by laws of physics and chemistry. Why would anyone become concerned about picking an apple or, say, picking an apple? Murder, rape, genocide, torture, or any heinous act cannot be criticized in the materialist view, IF, they are to be consistent.