Does good and evil exist?/Examining scenarios to prove statement

My opponent argues that good and evil do not exist through the extension of saying that objective morality (morality and immorality) does not exist. *Scenario* I did not argue that person A did not have a reason for killing person B. I did say that person A"s decision to kill person B was not based on the conversation that they happened to be having at the moment"that anything A or B brought up in the conversation did not spur A to do anything to B. For all we know, A could have had a prior reason for killing B, but whether or not person A had planned on killing B in advance is beside the point. I understand the point of my opponent"s argument against the scenario, as there are many factors which can lead to the killing of another person at a particular time. However, in deciding whether an action is good or evil, one can definitely take into account the context of the action being done. I will discuss more of this point in the Objective Morality section. *Objective Morality* My opponent argues that people have dissenting views over what is moral and immoral and thus objective morality does not exist. The fact that some cultures view that killing is moral in certain situations (e.g. human sacrifice) is an example of moral relativism. [1] Despite the fact that cultures may disagree with whether certain actions are morally right or wrong, the fact that there are certain standards in place shows that there are moral principles that they are working from. For example, the Aztecs participate in human sacrifice, which they consider moral because they are giving up their lives for something greater. One instance is the New Fire ceremony, in which humans were sacrificed in order to give the gods the strength to prevent the end of the world for another 52 years. [2] To an outsider, human sacrifice might be immoral because of the killing of individuals, but it is also possible the outsider might agree that the idea of keeping the world alive for future generations is morally sound. My opponent argues that most people will not kill unless there is a good reason. I would think that this statement in itself is something that would be agreed upon universally--even those who might be incapacitated would have their reasons to kill, even if they don"t believe killing is wrong. To kill someone needlessly would be pointless--if we were completely uninhibited with our killing, many of us (or perhaps all of us) would likely be dead. Thus, there is some standard of life that we hold, even if life in certain cases is less prioritized. While I agree with my opponent that people may not agree on what actions are good or evil, there are still principles that people aspire to either live by or ignore. I bring this up because my opponent is denying the existence of objective morality by bringing up the case of relativism, but my opponent has not convinced me that relativism can completely negate objective morality. I would like to ask my opponent for specific clarification on the definition of relativism that he/she is using. I would also like to request that my opponent expand his/her position on relativism in regards to the scenario. Person A"s killing of B might not be considered immoral because he did not know that killing was immoral, as my opponent brings up. But suppose that A believed that killing B was immoral but did it anyways. Would that not indicate that A is going against a principle that he believes he should be living by but goes against it because he believes in something he believes is better or more interesting? Or, in contrast, is A"s decision to kill B the moral decision because to not do kill B would be immoral? [1]: http://en.wikipedia.org... [2]: http://en.wikipedia.org...