Problem is, without God, morality is just a social/biological construct. Meaning, the reason people don't go around murdering others is either because society would frown upon such actions, or because they are slaves to chemical reactions in their brains.
Without God, morality becomes subjective/relative. You may "feel" that by raping someone, you are doing a bad thing, but without God, that is just an evolutionary mutation to keep a species thriving and healthy. This is similar to a farmer doing good things to keep his crops thriving and healthy. But is he morally bankrupt if he fails his crops? Just like it doesn't mean the rapist is any more "morally wrong" then the non-rapist.
Atheists may not act immorally because either they don't want to be thrown in jail, have yet to grasp the consequences of their worldview, or they may simply go with the flow of their emotions (which are purely chemical according to atheism), which tell them to act morally.
On atheism, you don’t rape people because of chemicals in your brain. It’s just like taking a drug. You do it to feel good. There is nothing objective about that.
Without God, there is nothing objectively wrong with committing rape. After all, the rapist doesn't feel bad about committing rape. Or at least not enough to avoid doing it. Preferring a murderous lifestyle to an upstanding citizen lifestyle is no more objectively right then preferring blue over red.
What makes morality remotely objective on atheism? A random unguided process of natural selection and random mutations on clumps of chemicals?
According to atheism, the only real way to get life is through purely naturalistic evolution (another topic altogether), but that is an entirely mindless process, just like stars fusing hydrogen into helium. Just because that process results in humans feeling moral emotions because it helps the species survive doesn't mean that those moral emotions are objective and set, like the law of gravity. There really is no legitimate reason to obey your "programming" other than simply to feel good. To respond to the chemical reactions in the brain that make you want to do "good" and not do "bad".
Furthermore, there is no ultimate point to morality on atheism because there is no eternity, regardless of punishment/non-punishment, the human race will eventually die out and the universe will cease to exist. All our accomplishments and self-sacrifice will have no effect in the end. Even if you subscribe to the ridiculous theory of an oscillating universe, things done in this universe will have no effect on the next.
All that being said, I’m not saying all atheists are, by default, bad people. I'm saying that an inevitable consequence of an atheistic worldview is relative morality. Which makes the worldview extremely disturbing. Most atheists don't seem to understand the implications of their worldview, so they can (ironically) live in blissful ignorance.
I feel that if the world became an atheist planet, with no religious people, over many generations good atheists would become a minority and nihilists would take over. Then, as the public began to understand the implications of their worldview, eventually humanity would either revert to the Stone Age or self-exterminate. In the end, without a God, morality is ultimately pointless. And this is just one of many extremely disturbing implications of the atheist worldview.
So, to any atheists reading this, next time you condemn religious people for "forcing" religion on their children, condemn the Westboro Baptist church for protesting funerals, condemn abortion clinic bombings, or even condemn Ted Bundy or Jeffrey Dahmer, think to yourself, "What right do *I* have to condemn these people? They simply have a different lifestyle preference than mine, what is objectively wrong about it? How is it different from condemning someone for having a different favorite color then me?”
Or alternatively, you could think "Hey, I feel in my heart morality is real, so there must be a source for morality. Maybe the idea of "God" isn't so crazy after all. Maybe this "Bible" isn't just a bronze-age fairy tale with no basis in history or science! Maybe I just need to give them an objective chance, rather than looking at them with presuppositions and disgust, or going by hearsay on atheist-dominated forums."
Think about these things when you lie down in bed tonight!