Well, if you're an atheist, then people are nothing more than "animate material", aren't they? What's wrong with a strong ape getting rid of a weak ape, especially if it's going to be a burden? Who cares? It's just a blob of flesh.
Oh, and you say that "most" people subscribe to this belief. What about those who don't? Who are you to judge them? You're just an "ape" like they are.
We don't see souless animals acting in this fashion. When a member of a dolphin pod is injured the other dolphins gather around to protect it and keep it from drowning. When a member of a wolf pack is injured, the others make sure it still gets food and is cared for. The skeletal remains of Smilodons (saber-toothed cats) indicate severely-injured individuals were well cared for by others. Why would humans do anything less, even without divine command?
We could all prey on the weak, killing each other at will. But then, societal life would be impossible. I've made a decision to agree to live by and uphold certain societal norms, so we can work to the benefit of all mankind. Its very much a golden-rule type situation.
Oh, and you say that "most" people subscribe to this belief. What about those who don't?
They cannot coexist in a civil society. So they can either go to prison, or they can have fun in a chaotic free-for-all like Somalia.
Who are you to judge them? You're just an "ape" like they are.
No, I'm a man. And this country is a community of men and women, so we get to set the rules.