I'm sure I've gone through this elsewhere in these forums, but I'll reiterate it again here:
When human societies were first forming, in the early stages of the development of the human species, we learned that we survive a heck of a lot better working as a group as opposed to working as individuals. Obviously, a group has to have trust in its individual components for the whole to function properly. If a person steals, it hurts the group. If a person kills, it hurts the group. Physical harm hurts the group, which makes it harder for the group to survive.
That at least covers the most basic, physiological needs.
Maslow shows us that there's more to the needs of humans, though, than the physiological. Ironically, not only are many of the needs created on the upper tiers of his Heirarchy of Needs (e.g. belonging, respect of others) a direct byproduct of the need to operate as a group to more adequately meet the needs of the first tier and most of the second tier, but they also can be met through further cooperation within the very group that instigated them.
It's interesting that religion is nowhere to be found on Maslow's Heirarchy of Needs. That isn't to imply that it isn't needed by humans (after all, this guy Maslow and his ideas should be placed under the same amount of scrutiny as anyone and anything else--he's a human, and therefore not without flaws); it simply implies that it isn't needed for a rational, secular explanation of the needs of people, and how we can see that laws governing the actions of the group can be derived wholly from a secular standpoint for these highly secular needs.
I don't mind that people have religion--I'm a spiritual person myself (though I follow no organized religion). I just have some issues when people imply that morality is exclusive to religion...more specifically, to
their religion...and even more specifically, to their
interpretation of their religion. I'd challenge any dogmatic person who acts this way to tell someone of another faith (e.g. Ghandi, the Dalai Lama, or atheistic scientists that research medicine to benefit mankind, if you are a Christian) that they are (or were, as in the case of the late Ghandi) immoral.
People prove every single day that they don't need religion to be moral. Likewise, other people prove every single day that religion doesn't deter them from being immoral. Just open your eyes and meet some folks, be they everyday Joe Atheists or genocidal Bob Enyarts.