I attended a sixth form debating society meeting once where the topic was “without God there is no such thing as morality, therefore the existence of morals shows that God exists” or something like that. It was a really interesting discussion, and I found that my thinking was challenged, because I would have said the above statement was true, but eventually changed my mind.
I would have probably said something along the lines of “without God, where else could our moral standards have come from?” Now, I’m fairly sure that any society can develop the concept of morality and have moral standards without having any religious/spiritual beliefs at all. I wouldn’t dispute that moral systems can be invented and implemented in society through other things than religion.
However, if you argue that all moral systems are constructs of human society, then no moral system has absolute authority, because it’s all relative. Without God you can say, “it is wrong to kill a platypus for fun, according to the moral code of my society” but what you can’t say is, “it is always wrong to kill a platypus for fun, regardless of the society in which the killing takes place”. In other words, it is impossible to claim that anything is either universally right or universally wrong without a universal standard to compare to. I hope that I is making sense.
Basically, without God there is no such thing as “good and evil” or “right and wrong”, there is only “acceptable within this society” and “unacceptable within this society”. Let’s say we come across an ancient tribe somewhere, who hold among their values that it is good and right to commit murder, as long as the victim was not in pyjamas at the time. We would disagree, and argue that it is not good or right to murder anyone, no matter what clothes they happen to be wearing. However, on what basis can we, the members of society A, persuade members of society B that their moral code is skewed unless we have an external moral code to which we can compare the moral codes of both societies?
Relative morals are like relative tape measures. If my tape shows my foot is 10cm long and someone else’s tape makes it out to me 10km long then how do we know what my actual foot size is? We need a measuring tool that conforms to a universal standard. In the case of morality, I believe that God gives us a universal standard by which all actions can be measured. Without God all you have is relative, unauthoritative rules made up by people.
While I was pondering all this, I thought that someone would probably come up with an argument like this: “there is a universal standard already built in to the human race – pain. Whatever causes others pain is evil, whatever relieves it is good”. That sounds fairly convincing until you come to the question of honesty. Is it more morally right for a man having an extra-marital affair to confess it to his wife, or to keep it a secret? I hope most people would say that telling the truth is the right thing to do, but in this case it would cause more pain.