Without intending any offense, I have to say that the argument that morality can only stem from religion is immature and demeaning.
To hold this viewpoint one must make certain assumptions about the nature of humanity.
First, it must be assumed that man is inherently immoral. That's easy if you're the type that believes in a Garden of Eden and Original Sin, but most of us like to think we are nice people, and our friends and family are too.
You must also assume that man is incapable of mature thought and reason. The argument is that the only thing preventing us from behaving evily is the threat of some supernatural punishment--treating all of us as if we are children who behave only to avoid a spanking.
I, for one, behave civily and with respect for others for a very logical (and ancient) reason: I'd want others to behave that way towards me. That's a bit of a simplification, but it does define a moral stance and requires no religion, dogma, or threat of eternal damnation.
There is again the unspoken assumption that "religious" implies "moral". As the studies and books linked in my first post explain, that is simply an urban myth.
Another undercurrent of the argument for religion based morality is the desire for absolutes in moral terms. But where are the absolutes in the Bible-based morality makers of this argument would have us obey? Is it absolute that "Thou shalt not kill?"--no, of course not. Soldiers kill, states execute, eople defend themselves and their loved ones. So already we have to introduce some semblance of relativity/situationally applied morality--the absolute is, well, not.
(Aside here. Many times I use "Thou shalt not kill" as an example, because it is specific, from the Ten commandments, and familiar. Often some guy will chime in and say "But it should say, 'Thou shalt not murder'." To that person, I ask, before you say it, tell me, are you admitting there are errors in the bible? And what is your point anyway (they always say that and only that) )
What about the other rules in the book many hold as absolute example of morality? The bible states very explicityly that the seventh day is the Lord's day, and no work shall be done on it, under penalty of death. But who today would consider it moral to kill the delivery boy for brining you your Sunday paper? Not I, and I suspect, not you.
In summation. Morality without religion is not only possible, but straightforward and undeniable. (But if you like thinking about this, you might enjoy this book: http://www.amazon.com/gp/product/0805075208/103-0432759-8192669?v=glance&n=283155 ) Those who argue that their religion holds the key to morality nevertheless behave no more morally than other people (really. Chirstians need to get their shit together and lead by example, but they haven't, and until they [as a group now] do, they are hypocrites). And finally, the so-called absolute morality of the Bible is neither absolute nor moral.