I think a lot of people would very heavily question inborn morality in humans; it's more commonly put down to social factors.
And Tpt, that's unfair to religious people. They don't necessarily act morally out of fear; they do it because they know there is a third-party system of arbitration which says it is the right thing to do, and they know it. An atheist can never know that because there is nothing out there making judgments except for each other.
Omega, but surely if you could remove that sense of honour and be happier for it, that would be the rational thing to do? Some might- very reasonably- say that your sense of honour is merely obstructing your own potential. Those without such a sense are no endemically less happy than you, and perhaps endemically more; after all, the less restrictions you live with and get away with, the happier you are going to be.
Humanism is a very difficult area- and the most difficult thing of all is its self-justification. Morals, ultimately, don't do anything other than obstruct you. Society can certainly do without them, IF it is properly run. So why bother?
The difference between a hardcore atheist and a not hardcore one, Omega? One for you to think about, that...