This is a good point - but if there were no belief in God - I still claim a belief in God would arise - either that or they would worship something (let's say King X);
I agree, but really, you're just making an in-place substitution of God for "King X". Would doctrine and prescriptions stay the same? Probably not, and this is why I think our world would be different to some degree.
Making a world without God would entail changing the course of history because God-based doctrine would probably be different than what we currently have. There would be no Moses, no Muhammad, no Jesus...it would likely be totally different in that regard.
Thus, in the same sort of effect, Newton would study the writing of King X, Galileo would still be persecuted for going against something King X claimed, Newton and Galileo would probably still have become scientists.
This is granting that all other things remain exactly the same, and why this is an error on your part.
However, I loved reading your post and it is a complete possibility as well - just taking into account that people remain largely the same, act largely the same regardless of a lot of things - so that the world would still progress as it had done.
Thanks, but I think you should know that I believe that if God doesn't exist, then life doesn't exist, nor does the Universe.
Speaking philosophically, though, I think that the lack of God removes an ultimate reason for human beings to exist, so without this reason, there wouldn't be intelligent beings...just a planet ruled by animals - no intelligence, no science, no nothing. Just a pointless existence.
I think the reason we have the ability to hope, to imagine, to see things bigger than ourselves and ponder the metaphysical is because there is a God in an abstract reality.
I believe all these things would be meaningless and no longer a part of the human experience if a being that would fit into these facets of humanity didn't exist.