Some of the fundamentals things about being atheist is seeing through all the bullshit problems of the presentation of creation in the bible. One such thing is the idea of the all powerful creator taking a whole week to create everything, when everything (according to the holy scripture) is the earth and our solar system plus a vague idea of “a lot of stars”.
A week. Because God is so perfect so awesome and powerful it can be done, but, hold on, if it took a week does it not mean that the all-powerful and unlimited is actually limited – when in top speed God can create a part of our visible universe in a week. Actually not a week, because God took the last day off to rest. Why would an perfect creator take time off – and from all things – to rest?, that implies that God got tired, can God be tired?.
Some would argue that the idea of the week is to make us humble humans more comfortable, that on our limited perception of time (which is indeed limited) we can not grasp the actions and the speed in which the creator acts. For those flexible believers those 6 days of work (plus one of rest) can be pressed into the first moments of the big bang or stretched across hundreds of millions of years until, say, the earth forms and starts to cool.
Here we get to a second, maybe even more important point, we are told that the bible (old testament) is the word of God, it was given to the Hebrews and it – literally, the book of God made by God, if so, why would the perfect makers who is also the perfect author of books not avoid mentioning time altogether and walk around this problematic issue of timing (and maybe also not to be embarrassed by the one day rest thing).
To us atheists it is simple, no mystery here, this was made up by humans, who desperately needed to explain a lot of things like who made what (God) when did it happen (in the beginning) and for whom was it made (why us of course), these ancient authors also added to this a format of the days of the week, as long as you’re laying down the basic rules might as well frame time into days. If a perfect creator would exist this being would probably not need to rest and would not take a week to work his magic.