These biblical answers seem more rational than 6k;
The Bible doesn't say that the earth is 6000 years old. The Genesis creation account reveals a "RE-CREATION" [a refurbishing] of the earth, because something destroyed it and made it "without form and void."
Before that destruction, when God first made the universe and the earth... the Bible doesn't mention how long the earth had existed.
The chronology of the Genesis creation account doesn't say how old the earth is. It tells us that God remade the destroyed earth to "support man" and gives us an indication of how long man has been on it [approximately 5000 to 6000 years].
First, God creates heaven and earth.
Then, something happens. The text does not tell us what happens.
After this has happened, the earth is without form - chaos, darkness.
Then, the text tells us that the Spirit of God visits this chaos, and how God turns the chaos in something good.
So, in this explanation, the seven days of creation are not the first creation: they are a later creation. I think that God does not create chaos: if He creates something, it is good. So, after the first creation of heaven and earth, something has happened that made that the earth was no longer as God meant it to be. This may - but that is only speculation - have been the downfall of the devil/Satan and the angels that were cast from heaven with him. Or it may have been the meteorite impact that scientist conjecture that has taken place. Or, it may have been both of these. Or something else. In any case: something has happened that turned Gods first good creation into something chaotic, but we are not told in the text what it exactly was. Then, Genesis tells that God made the chaos into the world of which God saw that it was good.
With this interpretation of Genesis 1: 1-2, one cannot tell from the Bible how old the earth is. This is not a problem, as the Bible is no science book, but a book of faith.
Seems more reasonable than 6000 years.
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