I've been watching a lot of religious debates recently, and often times people like William Lane Craig and Frank Turek will argue that without God there are no moral "oughts"; they claim that objective moral values do not exist without God because death is final and everyone ends up in the same place. They assume that without God you can't say whether anything is right or wrong--its just particles in motion.
But this argument is awful for several reasons. For starters, this argument pretends that people aren't choosing a morality and that it is absolutely determined by what Christopher Hitchens would call a celestial dictatorship. But that just depends on your society, culture, interpretation, mood, etc. You select the God and interpretation that aligns with your moral values and so its really no different than an atheist selecting their moral values to work best in society. So you can't say whether anything is right or wrong either because you would have an entirely different morality in bronze age Palestine, or if you grew up in North Korea. If morality is relative anyways, then the concept of moral oughts are ultimately fallacious; its all a matter of perspective and interpretation regardless if you believe or dont which really means the difference is moot.
As WLC would ask, "How do you know rape is wrong?"
I would say its wrong because a society of empowered, free women is much more effective and pleasant, and rape is a sinister attack on that. WLC would reply, but how do you know that's wrong? You're just responding to societal pressures and laws as well as evolutionary changes. I would then rebuttal him by saying that he's also just responding to social pressures because if you lived in bronze age Palestine then its very possible you would think rape is okay since you'd fallaciously believe women are inferior. Morality is relative whether you believe in religion or not in conclusion, and therefore means objective morality doesn't exist. All that exists is a secular, utilitarian analysis of society that tells us how to create the most effective, pleasant society as possible. Most religious people adopt secular standards anyways because you certainly wouldn't want to take morals from Leviticus, or the old testament, and or exodus.