I think too many people are focused on the idea that without God, Allah, [insert deity or religious structure of your choice] that morality is somehow in danger. As a religious person, I say that is a load of bull. Without even getting into the ethics of the entire discussion, many of the worst people I have ever met claim to be very religious while some of the nicest and least judgemental people I have met are atheist, agnostic, [insert label here that they probably got wrong anyway].
If you look at what someone like Jean-Paul Sartre says, there is almost a greater need for some kind of morality if God doesn't exist, because that means that "anything is possible" in that there is no supernaturally ratified scheme of right and wrong. Our existence would unquestionably precede the essence, or underlying meaning, of our existence, and we would be responsible for fulfilling the meaning in our own life. We would be entirely responsible for the choices we make and must live with their consequences without any hope of spiritual remuneration. Life would in many ways be harder if there was no God, because, while no society would allow everything to be permissible, it would be our responsibility to create an ethical guideline which would increase the quality of our lives without excessively restricting people's freedom.
Whether you look at it from a religious or areligious standpoint, it essentially boils down to how does person X's behavior negatively affect those around them and how does it negatively affect society as a whole. If their behavior is detrimental to their own well-being or questionable when put through the lens of a religious system like Christianity, that doesn't mean it should be judged or punished if it does not have negative repercussions for those around them.
A good example would be someone who has a homosexual relationship versus someone who smokes crystal meth. Both of these behaviors are frowned upon by many people in society, with the latter frowned upon by just about everyone. So what is the real difference between the two? Both are morally reprehensible according to Judeo-Christian scripture as selfish and irresponsible.
Many people may be offended by a homosexual relationship, but the relationship itself does not involve them, and restricting that relationship or treating it as if it were incomparable to a heterosexual relationship is misguided because the social consequences of that relationship are relatively minor. The only people who are affected by it in a negative way are those who allow themselves to be affected by it in a negative way. An issue such as whether or not a homosexual couple should be allowed to adopt children is a better issue to debate about, but restricting that is also against society's interests since the kids would be better off with some parents rather than none.
On the other hand, someone who smokes crystal meth or indulges in any of the more dangerous narcotics is often a danger to themselves and those around them. Their behavior becomes unpredictable, and they can attack, kill, or steal from random strangers, their friends, and even their own family because of the mind-altering effects of the drug. Obviously, it is not in society's interest to have people taking narcotics. In many ways alcohol is far more dangerous than a drug like marijuana as well because it encourages far more socially disruptive behavior than its counterpart.
We had two bags of grass, seventy-five pellets of mescaline, five sheets of high-powered blotter acid, a salt shaker half full of cocaine, a whole galaxy of multi-colored uppers, downers, screamers, laughers…Also a quart of tequila, a quart of rum, a case of beer, a pint of raw ether and two dozen amyls. The only thing that really worried me was the ether. There is nothing in the world more helpless and irresponsible and depraved than a man in the depths of an ether binge. –Raoul Duke
It is hard to shed anything but crocodile tears over White House speechwriter Patrick Buchanan's tragic analysis of the Nixon debacle. "It's like Sisyphus," he said. "We rolled the rock all the way up the mountain...and it rolled right back down on us...." Neither Sisyphus nor the commander of the Light Brigade nor Pat Buchanan had the time or any real inclination to question what they were doing...a martyr, to the bitter end, to a "flawed" cause and a narrow, atavistic concept of conservative politics that has done more damage to itself and the country in less than six years than its liberal enemies could have done in two or three decades. -Hunter S. Thompson