The Fourth Day
The sun (and with it the moon and the stars) is not created until Day Four. But, how can this be, since we’ve already had light and morning and evening since Day One (not to mention plant life since Day Three)? Isn’t the sun required for these things to take place?
Ancient peoples knew more from personal experience about the sun, the moon, and the stars than we do—the movements of the heavenly bodies were part of their intimate, daily experience, whereas we spend very few nights of our lives out of doors—and they certainly understood that you can’t have morning and evening without the sun. The strange detail of God waiting to create the sun until Day Four is yet another indication that Genesis 1 is not trying to give us scientific knowledge as to how things were created, other than to say that God is clearly the cause and Creator of everything. Rather, one of the things Genesis 1 is trying to tell us is that nothing in all of creation is divine, and therefore nothing in all of creation should be worshipped. The sun has been worshipped widely since the earliest days of humanity; Genesis 1 makes it clear that this is foolish idolatry: only God is worthy of worship.
I doubt very much that any of us literally worships the sun, but I am certain that many of us struggle with idolatry, which is the sin of thinking that the things God made (money, sex, power, possessions) are more important to our lives than God himself.