However God did not create the heavens and the earth in 6 literal days.
The bible account says, "In the beginning God created the heavens and the earth." (Genesis 1.1) It does not put a timescale on that activity.
It then tells of how God created life on earth over 6 creative days - it doesn't say how long those days were either but the principle at 2 Peter 3.8 is interesting, "Dont let it escape your notice, dear friends, that with the Lord a single day is like a thousand years and a thousand years are like a single day." Not unreasonable for someone with no begining or end.
But that is flawed, like most of the bible and religious accounts.
The reason Christians quote that verse is in order to make each "day" of Creation as long as they want it to be. But that fails. The ORDER of several events in the Genesis Creation Myth is wrong: they can make a "day" 24 hours, 1 year, a million years, or any length of time and it won't change the ORDER of events.
1) The Genesis Creation Myth wrongly states that angiosperms - those vascular land plants with seeds protected by fruits - appeared before any animals at all. That's wrong. The Cambrian "explosion" - which itself is not the first appearance of animal life - started about 530 million years ago: that's more then 300 million years BEFORE the first angiosperms.
2) The Genesis Creation Myth wrongly states that birds appeared before land animals. That's wrong too. First, birds evolved from certain land animals: certain reptiles. Second, land animals - even if we ignore the earlier arthropods and stick to just vertebrates - appear back as far as 350 million years ago. The first birds don't show up for another 200 million years or so.
It doesn't matter how long they try to make a day: in fact, making a day longer simply makes the error larger.
and this goes on...
3) God created light and divided the light from the darkness.
You cannot seperate light from dark, dark happens because of the absence of light, light is an electromagnetic radiation from an energy source like a sun or star, without light there is automatically dark, you don't need a god to do this, it happens.
All this is from prescientific minds.