morality sans a belief in god?

While I accept that one can make a rational argument logically demonstrating the independence of God and morality (e.g., Euthyphro), I'm a little surprised by theists who attempt to argue that it's only through a belief in a creator God that one can be a 'moral' person.

Why? For one thing, we can empirically observe the fact that there are many seemingly moral people who are atheist and completely non-religious, so we can conclude that simply believing in a creator God isn't a requirement to being a moral person, i.e., someone who lives by a particular standard of what's right and wrong.

Moreover, we can empirically observe the fact that there are many religions and philosophies, including Buddhism, that have strong ethical and moral principles without being based on the idea of a creator God, many of their adherents being, at least superficially, moral people. From this, we can conclude that theism isn't necessarily the only theological/philosophical basis for morality.

Whether or not a theist accepts the validity of these systems is irrelevant.

As for the basis of Buddhist ethics and morality, which I'd say is ultimately empirical and pragmatic in nature rather than 'revealed,' the underlying principles are kamma — the idea that certain actions produce pleasant, painful or neutral feelings/results — and the principle of ahimsa or harmlessness. (For more of my thoughts about Buddhist morality, see this.)

I've also noticed that there's also some confusion when it comes to Buddhist morality in that some people ask, If Buddhism says everything is an illusion, what's the point of trying to be a moral person? Wouldn't just be a futile effort?

To begin with, as far as I'm aware, the Buddha never said that everything is an illusion (i.e., unreal or empty of substance), especially when it comes to actions and their results. In my opinion, this is most likely a misunderstanding of what the Buddha says in place like SN 22.95, which people sometimes try to apply to everything, including the principle of causality.

And since Buddhist morality is centred on the efficacy of actions and the intentions underlying them, a Buddhist can be a moral person even without a belief in God simply by constantly reflecting upon their actions of body, speech and mind, and whether they lead to self-affliction, to the affliction of others or to both (MN 61).