ok, let's cut to the chase: without carrot and stick, no god (real or dreamed up) could hold any sway over humans, or make us consider what he/she/it/they mean by right and wrong. The J/C God supposedly has the ultimate carrot and stick: Heaven and Hell, and, according to his PR boys, *constantly* refers to these imposed consequences in order to impose upon man a code of right and wrong. the entire bible backs me on this, so, no: this "assumption" is certainly not "in error"
Okay, King Prout, I'll stipulate for the sake of argument just as you say: No god could hold "any sway over humans" without "carrot and stick" -- whatever that means.
Still it seems to me humans "just naturally" have a great affinity for truth. And no human is ever compelled (by God at least) to accept any truth that he cannot validate for himself. Don't forget, God made man to be "free" in mind and action.
Yet I insist on a qualification to your statement: Humans who are interested in truth would be interested in God. The others can go "their own way," and take their own chances.
There is no "carrot and stick" here; there is only human reason and action, acting reasonably and in good faith.
If you have a different way of looking at this problem, I'd be most glad to hear you provide the details of how that would work -- without the foundation in truth which is God, I mean.
Thanks for writing!