I'm sorry but we know more or less how old the bible is.
https://www.gotquestions.org/how-old-is-the-Bible.html Every religious person agrees on this that the earth was created around 6k to 10k years ago according to the bible, we can easily prove this wrong with various dating methods that prove the earth is far older than this, humans are far older than this as well. Even if somehow the 7 days mentioned in the bible weren't really days, we can still prove the bible is wrong.
Yes we know approximately how old the Bible is or at least how long ago biblical knowledge was given to mankind.
Your other statement is false and easy to disprove. I am religious and I do not believe the earth was created 6 to 10 thousand years ago. This is very much not a universal view among religious people.
The Bible was never meant to be a calendar and it is in my opinion an error to try and treat it as one.