I agree on the moral repugnance of obedience-under-threat, but in my opinion, if there were enough evidence to make the existence of a Hell-threatening God the simplest explanation, it would be incumbent upon humanity to do whatever we could to oppose said deity. We're getting a bit sci-fi now, but you get my point.
"Okay," says my wife, "but what if the god were omnipotent?"
I can't really answer this question because I don't think the idea of omnipotence is even self-consistent. It is a semantic trick, not an actual definable concept.
The classic question is, "Could God create a stone so large even He couldn't lift it?" (Or, if you prefer the wisdom of the Simpsons, "Could God microwave a burrito so hot even He couldn't eat it?") Omnipotence by its very nature is self-contradictory. This hypothetical omnipotent being cannot have powers that contradict its other powers... and since the examples above show that some conceivable powers clearly contradict each other, it doesn't make sense to say that a being has all conceivable powers.
Omnipresence is similarly meaningless. Omniscience is at least a definable concept, but it is also inherently impossible because of Gödel's incompleteness theorems1, which roughly state that no system can ever fully describe itself. In other words, you could hypothetically have a near-omniscient being, but there would have to be some aspects of itself that remained unknown to it. This makes good intuitive sense, as well, because you get an infinite regress -- the mechanism that allows the hypothetical omniscient being to know that last teensy bit about itself must also be known to it, and the mechanism for knowing the mechanism must also be known, so on ad infinitum.
So I don't think we need to answer the question of, "Would you live your life any differently if there is an omnipotent being who" yada-yada-yada... the question is not fully parseable. However, we can answer the question, "Would you live your life any differently if there really was a magic sky daddy
I suppose the answer would be the same as, "What would you do if you lived under a repressive totalitarian government?" I can't say for sure that in all situations I would have the bravery to stand up and oppose injustice, but I'd like to think I would. Whether the repressive government is run by a bunch of humans or by an angry deity in the sky, I don't see as how it would make that much of a difference in our response.
1Thanks to reader eduardopadoan for reminding me of the name of this concept.