You still have to account for the 1500 years between the Pentecost and the Reformation and the carbon dating that shows the universe is quite a bit more than 6000 years old.
How long were Adam and Eve in the garden, before Satan showed up? After all, they did have access to the Tree of Life, didn't they?
Personally I don't think they were there for billions of years. I think it is more likely that, just as God created adult human beings, He probably created an "old" earth and universe. He could have done it, couldn't He? Anyhow, I consider myself a scientist (PhD in molecular biology, published research...) yet I believe in a literal interpretation of Genesis.
Yep, more than a couple of centuries older. It is about 6,245 years old, give or take a decade or two, according to my preacher.
Show us where it says anywhere in the Bible that the earth is only 6,000 years old.