The Babble as we know it was compiled about seventeen hundred and fifty years ago, based on that fact it is fair to call it approximately 2000 years old.
A fairly good general retelling of the bibles history. Though to be fair it is a bit of a straw man argument, because i do not think many sceptics would refer to it as a two thousand year old book. And if they do they are perhaps taking an average date for both testaments.
The Old Testament is the original Hebrew Bible, the sacred scriptures of the Jewish faith, written at different times between about 1200 and 165 BC.
So that would be a fair general estimate.