Guys: Would you ever rape and murder a girl?

[TheRocketSurgeon]

It's not all instinct, though. Children are born with a poor sense of empathy, and have to be carefully taught (and sometimes punished for choosing selfishness over others' feelings/safety) in order to develop this sense of moral feeling toward others, to place the worth of others as equal to their own, in the sense of not doing harm. If you were a parent, you'd already know that. Our brains are sponges for social coding, from language to behavior, and continue to develop until into early adulthood (~25 years old), so a person who may naturally be able to feel empathy can still do great harm if they are not taught to be good, social/moral creatures.

This could start a chicken-or-the-egg diversion, but I doubt that empathy and socialization require any teaching, only experience and guidance for the avoidance of disastrous experience. Children aren't born social because they are born without fully-developed brains, but if raised in complete cultural isolation a normal adult would not be violent nor selfish, only unable to communicate in the culture which he then encounters as an adult. Then again, he probably wouldn't be sane from the long-term isolation, and such an experiment would be a cruel atrocity, so can't prove this. Anyway, I suggest that it's culture and etiquette, not empathy which requires teaching.

You mistake me. I think empathy is an instinct (which fails to develop in sociopaths) that develops as our brains develop. On top of that, we overlay social programs that allow for group/herd instincts to keep us functional in the society in which we develop, by the absorbing the written and unwritten rules-- it's why children are such mimics of adult behavior. These are two instincts. Like all other instincts, people have/develop them to various degrees (sociopaths = zero), and when the separate systems come into conflict, it's clear that empathy can be overridden by other programs. It's why it's so important to shape and develop our natural empathy through good social programming, which includes rewarding "good"/empathic behaviors so that becomes a more-dominant program in situations where there is such conflict. 

Religion makes the claim that it is the only way to instill the proper social/moral program, and it follows from that belief that without religion, we can not be moral on our own. The problem is that the facts don't really back that up-- religion is one form of social program, yes, but it unfortunately comes with too many riders which state that empathy for others may be discarded, as in the case of certain forms of sin, or heresy, or against nonbelievers, etc. It's also why I'm willing to classify Marxism/Leninist communism as a religion, despite being godless. It has the same sets of artificial rules that can override natural empathy, even that learned as a child.

The fault in the thinking of the religionists, with regard to this question, is that there are numerous social instinct programs we can absorb that have nothing to do with religion, and it's quite possible that (as you assert) a person with natural empathy would develop into a great person even in the absence of any social overlays... we can't really know the answer to that one, as you said. But with atheists, we see that there's a tendency to accept (and thus empathize with) others we don't see as part of our in-group, or rather that our definition of in-group is much broader, because we don't have a program specifically telling us to exclude them from the empathic in-group.

It's the great irony of the moral "conundrum" posed by the OP. Even recently a study showed that atheistic children were more empathic and kind than their religious-upbringing counterparts: http://www.forbes.com/sites/jvchamary/20...-morality/