Nowhere does the Bible say that God created the earth 4,000 years ago. I have read the entire Bible, and there is no verse anywhere that makes that claim. I believe what you are referring to are the calculations by Bishop Ussher, many centuries ago, which appear in the margins of some Bibles, and which give the supposed date of creation as around 4,000 B.C.(that would be 6,000 years ago).Well, the book is called the bible.. the story starts with something like "god created the heavens and the earth".. as for the the age of the earth, it debunks the claim that a god created the earth approx 4000 years ago.
But if the earth were created, it would make absolutely no difference whether the date of creation were six thousand years ago, or sixty billion years ago. No difference whatsoever.
The evolutionists look at their boxes of rocks and, like Bishop Ussher, make calculations and estimates. Even the evolutionists will admit that they weren't around when those bones settled into sediment and began their metamorphosis into stone. They've got theories. They've got guesses. They've got assumptions.
But in the end, all they've got is a box of rocks.