Why is belief in a higher power required?

[Esquilax]

Yes, it is true that many Christian morals are also evolutionarily beneficial, which is a reason that they are compatible with society, but I think there are holes in the atheist origin of morality. An example would be dying for an individual that is incapable of reproducing—a childless spouse or a senior citizen.
For instance, why shouldn't you spread lies about a classmate? She still gets to survive and reproduce. Say you know that there is no possibility of you ever needing her help in the near future.

I think you're making two major mistakes here; one is that you're pinning a definition of evolution as survival of the fittest, which isn't quite right. Natural selection- the selection mechanism for the evolutionary process- doesn't just select for advantageous traits, it actually selects against negative ones; so long as a trait doesn't provide sufficient negative effect to be fatally detrimental, it will persist. There are plenty of physical evidences for this in the human body, but it also extends to the heuristics that we as people employ in our day to day lives; even if I were to accept your examples as true, the case would be that these are evolutionary holdovers that don't hurt us enough to be selected against. This is certainly true of many elements of, say, our pattern recognition abilities, and our inbuilt deference to authority.

The second mistake you've made is confusing the scope of this; humans evolved as a social species, our survival- back when it wasn't assured as it is in most first world countries today- was contingent on us being a part of a group that would co-operate to survive, and employ our strength in numbers, in addition to our fabulous brains, to thrive. Evolution is awfully general in the main, it can't instill specific enough heuristics to deal with the examples you've listed, and even if it could those things would run against the benefit we'd gain from our sense of empathy. The advantageous trait is "don't hurt each other" not "don't hurt each other, except when it's beneficial to you." That level of selfishness runs directly contrary to the advantageous spirit of the trait.

Oh, I guess there's three mistakes; you also seem to be thinking that evolution- in it's incorrect "survival of the fittest" form- is the morality we're ascribed. It's not; evolution is the method by which those morals have arisen in us.